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[linux-2.6.git] / fs / ntfs / inode.c

/**
 * inode.c - NTFS kernel inode handling. Part of the Linux-NTFS project.
 *
 * Copyright (c) 2001-2004 Anton Altaparmakov
 *
 * This program/include file is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as published
 * by the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program/include file is distributed in the hope that it will be
 * useful, but WITHOUT ANY WARRANTY; without even the implied warranty
 * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program (in the main directory of the Linux-NTFS
 * distribution in the file COPYING); if not, write to the Free Software
 * Foundation,Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

#include <linux/pagemap.h>
#include <linux/buffer_head.h>
#include <linux/smp_lock.h>
#include <linux/quotaops.h>
#include <linux/mount.h>

#include "ntfs.h"
#include "dir.h"
#include "inode.h"
#include "attrib.h"
#include "time.h"

/**
 * ntfs_test_inode - compare two (possibly fake) inodes for equality
 * @vi:         vfs inode which to test
 * @na:         ntfs attribute which is being tested with
 *
 * Compare the ntfs attribute embedded in the ntfs specific part of the vfs
 * inode @vi for equality with the ntfs attribute @na.
 *
 * If searching for the normal file/directory inode, set @na->type to AT_UNUSED.
 * @na->name and @na->name_len are then ignored.
 *
 * Return 1 if the attributes match and 0 if not.
 *
 * NOTE: This function runs with the inode_lock spin lock held so it is not
 * allowed to sleep.
 */
int ntfs_test_inode(struct inode *vi, ntfs_attr *na)
{
        ntfs_inode *ni;

        if (vi->i_ino != na->mft_no)
                return 0;
        ni = NTFS_I(vi);
        /* If !NInoAttr(ni), @vi is a normal file or directory inode. */
        if (likely(!NInoAttr(ni))) {
                /* If not looking for a normal inode this is a mismatch. */
                if (unlikely(na->type != AT_UNUSED))
                        return 0;
        } else {
                /* A fake inode describing an attribute. */
                if (ni->type != na->type)
                        return 0;
                if (ni->name_len != na->name_len)
                        return 0;
                if (na->name_len && memcmp(ni->name, na->name,
                                na->name_len * sizeof(ntfschar)))
                        return 0;
        }
        /* Match! */
        return 1;
}

/**
 * ntfs_init_locked_inode - initialize an inode
 * @vi:         vfs inode to initialize
 * @na:         ntfs attribute which to initialize @vi to
 *
 * Initialize the vfs inode @vi with the values from the ntfs attribute @na in
 * order to enable ntfs_test_inode() to do its work.
 *
 * If initializing the normal file/directory inode, set @na->type to AT_UNUSED.
 * In that case, @na->name and @na->name_len should be set to NULL and 0,
 * respectively. Although that is not strictly necessary as
 * ntfs_read_inode_locked() will fill them in later.
 *
 * Return 0 on success and -errno on error.
 *
 * NOTE: This function runs with the inode_lock spin lock held so it is not
 * allowed to sleep. (Hence the GFP_ATOMIC allocation.)
 */
static int ntfs_init_locked_inode(struct inode *vi, ntfs_attr *na)
{
        ntfs_inode *ni = NTFS_I(vi);

        vi->i_ino = na->mft_no;

        ni->type = na->type;
        if (na->type == AT_INDEX_ALLOCATION)
                NInoSetMstProtected(ni);

        ni->name = na->name;
        ni->name_len = na->name_len;

        /* If initializing a normal inode, we are done. */
        if (likely(na->type == AT_UNUSED))
                return 0;

        /* It is a fake inode. */
        NInoSetAttr(ni);

        /*
         * We have I30 global constant as an optimization as it is the name
         * in >99.9% of named attributes! The other <0.1% incur a GFP_ATOMIC
         * allocation but that is ok. And most attributes are unnamed anyway,
         * thus the fraction of named attributes with name != I30 is actually
         * absolutely tiny.
         */
        if (na->name && na->name_len && na->name != I30) {
                unsigned int i;

                i = na->name_len * sizeof(ntfschar);
                ni->name = (ntfschar*)kmalloc(i + sizeof(ntfschar), GFP_ATOMIC);
                if (!ni->name)
                        return -ENOMEM;
                memcpy(ni->name, na->name, i);
                ni->name[i] = cpu_to_le16('\0');
        }
        return 0;
}

typedef int (*set_t)(struct inode *, void *);
static int ntfs_read_locked_inode(struct inode *vi);
static int ntfs_read_locked_attr_inode(struct inode *base_vi, struct inode *vi);

/**
 * ntfs_iget - obtain a struct inode corresponding to a specific normal inode
 * @sb:         super block of mounted volume
 * @mft_no:     mft record number / inode number to obtain
 *
 * Obtain the struct inode corresponding to a specific normal inode (i.e. a
 * file or directory).
 *
 * If the inode is in the cache, it is just returned with an increased
 * reference count. Otherwise, a new struct inode is allocated and initialized,
 * and finally ntfs_read_locked_inode() is called to read in the inode and
 * fill in the remainder of the inode structure.
 *
 * Return the struct inode on success. Check the return value with IS_ERR() and
 * if true, the function failed and the error code is obtained from PTR_ERR().
 */
struct inode *ntfs_iget(struct super_block *sb, unsigned long mft_no)
{
        struct inode *vi;
        ntfs_attr na;
        int err;

        na.mft_no = mft_no;
        na.type = AT_UNUSED;
        na.name = NULL;
        na.name_len = 0;

        vi = iget5_locked(sb, mft_no, (test_t)ntfs_test_inode,
                        (set_t)ntfs_init_locked_inode, &na);
        if (!vi)
                return ERR_PTR(-ENOMEM);

        err = 0;

        /* If this is a freshly allocated inode, need to read it now. */
        if (vi->i_state & I_NEW) {
                err = ntfs_read_locked_inode(vi);
                unlock_new_inode(vi);
        }
        /*
         * There is no point in keeping bad inodes around if the failure was
         * due to ENOMEM. We want to be able to retry again later.
         */
        if (err == -ENOMEM) {
                iput(vi);
                vi = ERR_PTR(err);
        }
        return vi;
}

/**
 * ntfs_attr_iget - obtain a struct inode corresponding to an attribute
 * @base_vi:    vfs base inode containing the attribute
 * @type:       attribute type
 * @name:       Unicode name of the attribute (NULL if unnamed)
 * @name_len:   length of @name in Unicode characters (0 if unnamed)
 *
 * Obtain the (fake) struct inode corresponding to the attribute specified by
 * @type, @name, and @name_len, which is present in the base mft record
 * specified by the vfs inode @base_vi.
 *
 * If the attribute inode is in the cache, it is just returned with an
 * increased reference count. Otherwise, a new struct inode is allocated and
 * initialized, and finally ntfs_read_locked_attr_inode() is called to read the
 * attribute and fill in the inode structure.
 *
 * Return the struct inode of the attribute inode on success. Check the return
 * value with IS_ERR() and if true, the function failed and the error code is
 * obtained from PTR_ERR().
 */
struct inode *ntfs_attr_iget(struct inode *base_vi, ATTR_TYPES type,
                ntfschar *name, u32 name_len)
{
        struct inode *vi;
        ntfs_attr na;
        int err;

        na.mft_no = base_vi->i_ino;
        na.type = type;
        na.name = name;
        na.name_len = name_len;

        vi = iget5_locked(base_vi->i_sb, na.mft_no, (test_t)ntfs_test_inode,
                        (set_t)ntfs_init_locked_inode, &na);
        if (!vi)
                return ERR_PTR(-ENOMEM);

        err = 0;

        /* If this is a freshly allocated inode, need to read it now. */
        if (vi->i_state & I_NEW) {
                err = ntfs_read_locked_attr_inode(base_vi, vi);
                unlock_new_inode(vi);
        }
        /*
         * There is no point in keeping bad attribute inodes around. This also
         * simplifies things in that we never need to check for bad attribute
         * inodes elsewhere.
         */
        if (err) {
                iput(vi);
                vi = ERR_PTR(err);
        }
        return vi;
}

struct inode *ntfs_alloc_big_inode(struct super_block *sb)
{
        ntfs_inode *ni;

        ntfs_debug("Entering.");
        ni = (ntfs_inode *)kmem_cache_alloc(ntfs_big_inode_cache,
                        SLAB_NOFS);
        if (likely(ni != NULL)) {
                ni->state = 0;
                return VFS_I(ni);
        }
        ntfs_error(sb, "Allocation of NTFS big inode structure failed.");
        return NULL;
}

void ntfs_destroy_big_inode(struct inode *inode)
{
        ntfs_inode *ni = NTFS_I(inode);

        ntfs_debug("Entering.");
        BUG_ON(ni->page);
        if (!atomic_dec_and_test(&ni->count))
                BUG();
        kmem_cache_free(ntfs_big_inode_cache, NTFS_I(inode));
}

static inline ntfs_inode *ntfs_alloc_extent_inode(void)
{
        ntfs_inode *ni;

        ntfs_debug("Entering.");
        ni = (ntfs_inode *)kmem_cache_alloc(ntfs_inode_cache, SLAB_NOFS);
        if (likely(ni != NULL)) {
                ni->state = 0;
                return ni;
        }
        ntfs_error(NULL, "Allocation of NTFS inode structure failed.");
        return NULL;
}

void ntfs_destroy_extent_inode(ntfs_inode *ni)
{
        ntfs_debug("Entering.");
        BUG_ON(ni->page);
        if (!atomic_dec_and_test(&ni->count))
                BUG();
        kmem_cache_free(ntfs_inode_cache, ni);
}

/**
 * __ntfs_init_inode - initialize ntfs specific part of an inode
 * @sb:         super block of mounted volume
 * @ni:         freshly allocated ntfs inode which to initialize
 *
 * Initialize an ntfs inode to defaults.
 *
 * NOTE: ni->mft_no, ni->state, ni->type, ni->name, and ni->name_len are left
 * untouched. Make sure to initialize them elsewhere.
 *
 * Return zero on success and -ENOMEM on error.
 */
static void __ntfs_init_inode(struct super_block *sb, ntfs_inode *ni)
{
        ntfs_debug("Entering.");
        ni->initialized_size = ni->allocated_size = 0;
        ni->seq_no = 0;
        atomic_set(&ni->count, 1);
        ni->vol = NTFS_SB(sb);
        init_run_list(&ni->run_list);
        init_MUTEX(&ni->mrec_lock);
        ni->page = NULL;
        ni->page_ofs = 0;
        ni->attr_list_size = 0;
        ni->attr_list = NULL;
        init_run_list(&ni->attr_list_rl);
        ni->itype.index.bmp_ino = NULL;
        ni->itype.index.block_size = 0;
        ni->itype.index.vcn_size = 0;
        ni->itype.index.block_size_bits = 0;
        ni->itype.index.vcn_size_bits = 0;
        init_MUTEX(&ni->extent_lock);
        ni->nr_extents = 0;
        ni->ext.base_ntfs_ino = NULL;
        return;
}

static inline void ntfs_init_big_inode(struct inode *vi)
{
        ntfs_inode *ni = NTFS_I(vi);

        ntfs_debug("Entering.");
        __ntfs_init_inode(vi->i_sb, ni);
        ni->mft_no = vi->i_ino;
        return;
}

inline ntfs_inode *ntfs_new_extent_inode(struct super_block *sb,
                unsigned long mft_no)
{
        ntfs_inode *ni = ntfs_alloc_extent_inode();

        ntfs_debug("Entering.");
        if (likely(ni != NULL)) {
                __ntfs_init_inode(sb, ni);
                ni->mft_no = mft_no;
                ni->type = AT_UNUSED;
                ni->name = NULL;
                ni->name_len = 0;
        }
        return ni;
}

/**
 * ntfs_is_extended_system_file - check if a file is in the $Extend directory
 * @ctx:        initialized attribute search context
 *
 * Search all file name attributes in the inode described by the attribute
 * search context @ctx and check if any of the names are in the $Extend system
 * directory.
 *
 * Return values:
 *         1: file is in $Extend directory
 *         0: file is not in $Extend directory
 *      -EIO: file is corrupt
 */
static int ntfs_is_extended_system_file(attr_search_context *ctx)
{
        int nr_links;

        /* Restart search. */
        reinit_attr_search_ctx(ctx);

        /* Get number of hard links. */
        nr_links = le16_to_cpu(ctx->mrec->link_count);

        /* Loop through all hard links. */
        while (lookup_attr(AT_FILE_NAME, NULL, 0, 0, 0, NULL, 0, ctx)) {
                FILE_NAME_ATTR *file_name_attr;
                ATTR_RECORD *attr = ctx->attr;
                u8 *p, *p2;

                nr_links--;
                /*
                 * Maximum sanity checking as we are called on an inode that
                 * we suspect might be corrupt.
                 */
                p = (u8*)attr + le32_to_cpu(attr->length);
                if (p < (u8*)ctx->mrec || (u8*)p > (u8*)ctx->mrec +
                                le32_to_cpu(ctx->mrec->bytes_in_use)) {
err_corrupt_attr:
                        ntfs_error(ctx->ntfs_ino->vol->sb, "Corrupt file name "
                                        "attribute. You should run chkdsk.");
                        return -EIO;
                }
                if (attr->non_resident) {
                        ntfs_error(ctx->ntfs_ino->vol->sb, "Non-resident file "
                                        "name. You should run chkdsk.");
                        return -EIO;
                }
                if (attr->flags) {
                        ntfs_error(ctx->ntfs_ino->vol->sb, "File name with "
                                        "invalid flags. You should run "
                                        "chkdsk.");
                        return -EIO;
                }
                if (!(attr->data.resident.flags & RESIDENT_ATTR_IS_INDEXED)) {
                        ntfs_error(ctx->ntfs_ino->vol->sb, "Unindexed file "
                                        "name. You should run chkdsk.");
                        return -EIO;
                }
                file_name_attr = (FILE_NAME_ATTR*)((u8*)attr +
                                le16_to_cpu(attr->data.resident.value_offset));
                p2 = (u8*)attr + le32_to_cpu(attr->data.resident.value_length);
                if (p2 < (u8*)attr || p2 > p)
                        goto err_corrupt_attr;
                /* This attribute is ok, but is it in the $Extend directory? */
                if (MREF_LE(file_name_attr->parent_directory) == FILE_Extend)
                        return 1;       /* YES, it's an extended system file. */
        }
        if (nr_links) {
                ntfs_error(ctx->ntfs_ino->vol->sb, "Inode hard link count "
                                "doesn't match number of name attributes. You "
                                "should run chkdsk.");
                return -EIO;
        }
        return 0;       /* NO, it is not an extended system file. */
}

/**
 * ntfs_read_locked_inode - read an inode from its device
 * @vi:         inode to read
 *
 * ntfs_read_locked_inode() is called from ntfs_iget() to read the inode
 * described by @vi into memory from the device.
 *
 * The only fields in @vi that we need to/can look at when the function is
 * called are i_sb, pointing to the mounted device's super block, and i_ino,
 * the number of the inode to load. If this is a fake inode, i.e. NInoAttr(),
 * then the fields type, name, and name_len are also valid, and describe the
 * attribute which this fake inode represents.
 *
 * ntfs_read_locked_inode() maps, pins and locks the mft record number i_ino
 * for reading and sets up the necessary @vi fields as well as initializing
 * the ntfs inode.
 *
 * Q: What locks are held when the function is called?
 * A: i_state has I_LOCK set, hence the inode is locked, also
 *    i_count is set to 1, so it is not going to go away
 *    i_flags is set to 0 and we have no business touching it. Only an ioctl()
 *    is allowed to write to them. We should of course be honouring them but
 *    we need to do that using the IS_* macros defined in include/linux/fs.h.
 *    In any case ntfs_read_locked_inode() has nothing to do with i_flags.
 *
 * Return 0 on success and -errno on error. In the error case, the inode will
 * have had make_bad_inode() executed on it.
 */
static int ntfs_read_locked_inode(struct inode *vi)
{
        ntfs_volume *vol = NTFS_SB(vi->i_sb);
        ntfs_inode *ni;
        MFT_RECORD *m;
        STANDARD_INFORMATION *si;
        attr_search_context *ctx;
        int err = 0;

        ntfs_debug("Entering for i_ino 0x%lx.", vi->i_ino);

        /* Setup the generic vfs inode parts now. */

        /* This is the optimal IO size (for stat), not the fs block size. */
        vi->i_blksize = PAGE_CACHE_SIZE;
        /*
         * This is for checking whether an inode has changed w.r.t. a file so
         * that the file can be updated if necessary (compare with f_version).
         */
        vi->i_version = 1;

        vi->i_uid = vol->uid;
        vi->i_gid = vol->gid;
        vi->i_mode = 0;

        /*
         * Initialize the ntfs specific part of @vi special casing
         * FILE_MFT which we need to do at mount time.
         */
        if (vi->i_ino != FILE_MFT)
                ntfs_init_big_inode(vi);
        ni = NTFS_I(vi);

        m = map_mft_record(ni);
        if (IS_ERR(m)) {
                err = PTR_ERR(m);
                goto err_out;
        }
        ctx = get_attr_search_ctx(ni, m);
        if (!ctx) {
                err = -ENOMEM;
                goto unm_err_out;
        }

        if (!(m->flags & MFT_RECORD_IN_USE)) {
                ntfs_error(vi->i_sb, "Inode is not in use! You should "
                                "run chkdsk.");
                goto unm_err_out;
        }
        if (m->base_mft_record) {
                ntfs_error(vi->i_sb, "Inode is an extent inode! You should "
                                "run chkdsk.");
                goto unm_err_out;
        }

        /* Transfer information from mft record into vfs and ntfs inodes. */
        vi->i_generation = ni->seq_no = le16_to_cpu(m->sequence_number);

        /*
         * FIXME: Keep in mind that link_count is two for files which have both
         * a long file name and a short file name as separate entries, so if
         * we are hiding short file names this will be too high. Either we need
         * to account for the short file names by subtracting them or we need
         * to make sure we delete files even though i_nlink is not zero which
         * might be tricky due to vfs interactions. Need to think about this
         * some more when implementing the unlink command.
         */
        vi->i_nlink = le16_to_cpu(m->link_count);
        /*
         * FIXME: Reparse points can have the directory bit set even though
         * they would be S_IFLNK. Need to deal with this further below when we
         * implement reparse points / symbolic links but it will do for now.
         * Also if not a directory, it could be something else, rather than
         * a regular file. But again, will do for now.
         */
        if (m->flags & MFT_RECORD_IS_DIRECTORY) {
                vi->i_mode |= S_IFDIR;
                /* Things break without this kludge! */
                if (vi->i_nlink > 1)
                        vi->i_nlink = 1;
        } else
                vi->i_mode |= S_IFREG;

        /*
         * Find the standard information attribute in the mft record. At this
         * stage we haven't setup the attribute list stuff yet, so this could
         * in fact fail if the standard information is in an extent record, but
         * I don't think this actually ever happens.
         */
        if (!lookup_attr(AT_STANDARD_INFORMATION, NULL, 0, 0, 0, NULL, 0,
                        ctx)) {
                /*
                 * TODO: We should be performing a hot fix here (if the recover
                 * mount option is set) by creating a new attribute.
                 */
                ntfs_error(vi->i_sb, "$STANDARD_INFORMATION attribute is "
                                "missing.");
                goto unm_err_out;
        }
        /* Get the standard information attribute value. */
        si = (STANDARD_INFORMATION*)((char*)ctx->attr +
                        le16_to_cpu(ctx->attr->data.resident.value_offset));

        /* Transfer information from the standard information into vfs_ino. */
        /*
         * Note: The i_?times do not quite map perfectly onto the NTFS times,
         * but they are close enough, and in the end it doesn't really matter
         * that much...
         */
        /*
         * mtime is the last change of the data within the file. Not changed
         * when only metadata is changed, e.g. a rename doesn't affect mtime.
         */
        vi->i_mtime = ntfs2utc(si->last_data_change_time);
        /*
         * ctime is the last change of the metadata of the file. This obviously
         * always changes, when mtime is changed. ctime can be changed on its
         * own, mtime is then not changed, e.g. when a file is renamed.
         */
        vi->i_ctime = ntfs2utc(si->last_mft_change_time);
        /*
         * Last access to the data within the file. Not changed during a rename
         * for example but changed whenever the file is written to.
         */
        vi->i_atime = ntfs2utc(si->last_access_time);

        /* Find the attribute list attribute if present. */
        reinit_attr_search_ctx(ctx);
        if (lookup_attr(AT_ATTRIBUTE_LIST, NULL, 0, 0, 0, NULL, 0, ctx)) {
                if (vi->i_ino == FILE_MFT)
                        goto skip_attr_list_load;
                ntfs_debug("Attribute list found in inode 0x%lx.", vi->i_ino);
                NInoSetAttrList(ni);
                if (ctx->attr->flags & ATTR_IS_ENCRYPTED ||
                                ctx->attr->flags & ATTR_COMPRESSION_MASK ||
                                ctx->attr->flags & ATTR_IS_SPARSE) {
                        ntfs_error(vi->i_sb, "Attribute list attribute is "
                                        "compressed/encrypted/sparse. Not "
                                        "allowed. Corrupt inode. You should "
                                        "run chkdsk.");
                        goto unm_err_out;
                }
                /* Now allocate memory for the attribute list. */
                ni->attr_list_size = (u32)attribute_value_length(ctx->attr);
                ni->attr_list = ntfs_malloc_nofs(ni->attr_list_size);
                if (!ni->attr_list) {
                        ntfs_error(vi->i_sb, "Not enough memory to allocate "
                                        "buffer for attribute list.");
                        err = -ENOMEM;
                        goto unm_err_out;
                }
                if (ctx->attr->non_resident) {
                        NInoSetAttrListNonResident(ni);
                        if (ctx->attr->data.non_resident.lowest_vcn) {
                                ntfs_error(vi->i_sb, "Attribute list has non "
                                                "zero lowest_vcn. Inode is "
                                                "corrupt. You should run "
                                                "chkdsk.");
                                goto unm_err_out;
                        }
                        /*
                         * Setup the run list. No need for locking as we have
                         * exclusive access to the inode at this time.
                         */
                        ni->attr_list_rl.rl = decompress_mapping_pairs(vol,
                                        ctx->attr, NULL);
                        if (IS_ERR(ni->attr_list_rl.rl)) {
                                err = PTR_ERR(ni->attr_list_rl.rl);
                                ni->attr_list_rl.rl = NULL;
                                ntfs_error(vi->i_sb, "Mapping pairs "
                                                "decompression failed with "
                                                "error code %i. Corrupt "
                                                "attribute list in inode.",
                                                -err);
                                goto unm_err_out;
                        }
                        /* Now load the attribute list. */
                        if ((err = load_attribute_list(vol, &ni->attr_list_rl,
                                        ni->attr_list, ni->attr_list_size,
                                        sle64_to_cpu(ctx->attr->data.
                                        non_resident.initialized_size)))) {
                                ntfs_error(vi->i_sb, "Failed to load "
                                                "attribute list attribute.");
                                goto unm_err_out;
                        }
                } else /* if (!ctx.attr->non_resident) */ {
                        if ((u8*)ctx->attr + le16_to_cpu(
                                        ctx->attr->data.resident.value_offset) +
                                        le32_to_cpu(
                                        ctx->attr->data.resident.value_length) >
                                        (u8*)ctx->mrec + vol->mft_record_size) {
                                ntfs_error(vi->i_sb, "Corrupt attribute list "
                                                "in inode.");
                                goto unm_err_out;
                        }
                        /* Now copy the attribute list. */
                        memcpy(ni->attr_list, (u8*)ctx->attr + le16_to_cpu(
                                        ctx->attr->data.resident.value_offset),
                                        le32_to_cpu(
                                        ctx->attr->data.resident.value_length));
                }
        }
skip_attr_list_load:
        /*
         * If an attribute list is present we now have the attribute list value
         * in ntfs_ino->attr_list and it is ntfs_ino->attr_list_size bytes.
         */
        if (S_ISDIR(vi->i_mode)) {
                struct inode *bvi;
                ntfs_inode *bni;
                INDEX_ROOT *ir;
                char *ir_end, *index_end;

                /* It is a directory, find index root attribute. */
                reinit_attr_search_ctx(ctx);
                if (!lookup_attr(AT_INDEX_ROOT, I30, 4, CASE_SENSITIVE, 0,
                                NULL, 0, ctx)) {
                        // FIXME: File is corrupt! Hot-fix with empty index
                        // root attribute if recovery option is set.
                        ntfs_error(vi->i_sb, "$INDEX_ROOT attribute is "
                                        "missing.");
                        goto unm_err_out;
                }
                /* Set up the state. */
                if (ctx->attr->non_resident) {
                        ntfs_error(vi->i_sb, "$INDEX_ROOT attribute is "
                                        "not resident. Not allowed.");
                        goto unm_err_out;
                }
                /*
                 * Compressed/encrypted index root just means that the newly
                 * created files in that directory should be created compressed/
                 * encrypted. However index root cannot be both compressed and
                 * encrypted.
                 */
                if (ctx->attr->flags & ATTR_COMPRESSION_MASK)
                        NInoSetCompressed(ni);
                if (ctx->attr->flags & ATTR_IS_ENCRYPTED) {
                        if (ctx->attr->flags & ATTR_COMPRESSION_MASK) {
                                ntfs_error(vi->i_sb, "Found encrypted and "
                                                "compressed attribute. Not "
                                                "allowed.");
                                goto unm_err_out;
                        }
                        NInoSetEncrypted(ni);
                }
                if (ctx->attr->flags & ATTR_IS_SPARSE)
                        NInoSetSparse(ni);
                ir = (INDEX_ROOT*)((char*)ctx->attr + le16_to_cpu(
                                ctx->attr->data.resident.value_offset));
                ir_end = (char*)ir + le32_to_cpu(
                                ctx->attr->data.resident.value_length);
                if (ir_end > (char*)ctx->mrec + vol->mft_record_size) {
                        ntfs_error(vi->i_sb, "$INDEX_ROOT attribute is "
                                        "corrupt.");
                        goto unm_err_out;
                }
                index_end = (char*)&ir->index +
                                le32_to_cpu(ir->index.index_length);
                if (index_end > ir_end) {
                        ntfs_error(vi->i_sb, "Directory index is corrupt.");
                        goto unm_err_out;
                }
                if (ir->type != AT_FILE_NAME) {
                        ntfs_error(vi->i_sb, "Indexed attribute is not "
                                        "$FILE_NAME. Not allowed.");
                        goto unm_err_out;
                }
                if (ir->collation_rule != COLLATION_FILE_NAME) {
                        ntfs_error(vi->i_sb, "Index collation rule is not "
                                        "COLLATION_FILE_NAME. Not allowed.");
                        goto unm_err_out;
                }
                ni->itype.index.block_size = le32_to_cpu(ir->index_block_size);
                if (ni->itype.index.block_size &
                                (ni->itype.index.block_size - 1)) {
                        ntfs_error(vi->i_sb, "Index block size (%u) is not a "
                                        "power of two.",
                                        ni->itype.index.block_size);
                        goto unm_err_out;
                }
                if (ni->itype.index.block_size > PAGE_CACHE_SIZE) {
                        ntfs_error(vi->i_sb, "Index block size (%u) > "
                                        "PAGE_CACHE_SIZE (%ld) is not "
                                        "supported. Sorry.",
                                        ni->itype.index.block_size,
                                        PAGE_CACHE_SIZE);
                        err = -EOPNOTSUPP;
                        goto unm_err_out;
                }
                if (ni->itype.index.block_size < NTFS_BLOCK_SIZE) {
                        ntfs_error(vi->i_sb, "Index block size (%u) < "
                                        "NTFS_BLOCK_SIZE (%i) is not "
                                        "supported. Sorry.",
                                        ni->itype.index.block_size,
                                        NTFS_BLOCK_SIZE);
                        err = -EOPNOTSUPP;
                        goto unm_err_out;
                }
                ni->itype.index.block_size_bits =
                                ffs(ni->itype.index.block_size) - 1;
                /* Determine the size of a vcn in the directory index. */
                if (vol->cluster_size <= ni->itype.index.block_size) {
                        ni->itype.index.vcn_size = vol->cluster_size;
                        ni->itype.index.vcn_size_bits = vol->cluster_size_bits;
                } else {
                        ni->itype.index.vcn_size = vol->sector_size;
                        ni->itype.index.vcn_size_bits = vol->sector_size_bits;
                }

                /* Setup the index allocation attribute, even if not present. */
                NInoSetMstProtected(ni);
                ni->type = AT_INDEX_ALLOCATION;
                ni->name = I30;
                ni->name_len = 4;

                if (!(ir->index.flags & LARGE_INDEX)) {
                        /* No index allocation. */
                        vi->i_size = ni->initialized_size =
                                        ni->allocated_size = 0;
                        /* We are done with the mft record, so we release it. */
                        put_attr_search_ctx(ctx);
                        unmap_mft_record(ni);
                        m = NULL;
                        ctx = NULL;
                        goto skip_large_dir_stuff;
                } /* LARGE_INDEX: Index allocation present. Setup state. */
                NInoSetIndexAllocPresent(ni);
                /* Find index allocation attribute. */
                reinit_attr_search_ctx(ctx);
                if (!lookup_attr(AT_INDEX_ALLOCATION, I30, 4, CASE_SENSITIVE,
                                0, NULL, 0, ctx)) {
                        ntfs_error(vi->i_sb, "$INDEX_ALLOCATION attribute "
                                        "is not present but $INDEX_ROOT "
                                        "indicated it is.");
                        goto unm_err_out;
                }
                if (!ctx->attr->non_resident) {
                        ntfs_error(vi->i_sb, "$INDEX_ALLOCATION attribute "
                                        "is resident.");
                        goto unm_err_out;
                }
                if (ctx->attr->flags & ATTR_IS_ENCRYPTED) {
                        ntfs_error(vi->i_sb, "$INDEX_ALLOCATION attribute "
                                        "is encrypted.");
                        goto unm_err_out;
                }
                if (ctx->attr->flags & ATTR_IS_SPARSE) {
                        ntfs_error(vi->i_sb, "$INDEX_ALLOCATION attribute "
                                        "is sparse.");
                        goto unm_err_out;
                }
                if (ctx->attr->flags & ATTR_COMPRESSION_MASK) {
                        ntfs_error(vi->i_sb, "$INDEX_ALLOCATION attribute "
                                        "is compressed.");
                        goto unm_err_out;
                }
                if (ctx->attr->data.non_resident.lowest_vcn) {
                        ntfs_error(vi->i_sb, "First extent of "
                                        "$INDEX_ALLOCATION attribute has non "
                                        "zero lowest_vcn. Inode is corrupt. "
                                        "You should run chkdsk.");
                        goto unm_err_out;
                }
                vi->i_size = sle64_to_cpu(
                                ctx->attr->data.non_resident.data_size);
                ni->initialized_size = sle64_to_cpu(
                                ctx->attr->data.non_resident.initialized_size);
                ni->allocated_size = sle64_to_cpu(
                                ctx->attr->data.non_resident.allocated_size);
                /*
                 * We are done with the mft record, so we release it. Otherwise
                 * we would deadlock in ntfs_attr_iget().
                 */
                put_attr_search_ctx(ctx);
                unmap_mft_record(ni);
                m = NULL;
                ctx = NULL;
                /* Get the index bitmap attribute inode. */
                bvi = ntfs_attr_iget(vi, AT_BITMAP, I30, 4);
                if (unlikely(IS_ERR(bvi))) {
                        ntfs_error(vi->i_sb, "Failed to get bitmap attribute.");
                        err = PTR_ERR(bvi);
                        goto unm_err_out;
                }
                ni->itype.index.bmp_ino = bvi;
                bni = NTFS_I(bvi);
                if (NInoCompressed(bni) || NInoEncrypted(bni) ||
                                NInoSparse(bni)) {
                        ntfs_error(vi->i_sb, "$BITMAP attribute is compressed "
                                        "and/or encrypted and/or sparse.");
                        goto unm_err_out;
                }
                /* Consistency check bitmap size vs. index allocation size. */
                if ((bvi->i_size << 3) < (vi->i_size >>
                                ni->itype.index.block_size_bits)) {
                        ntfs_error(vi->i_sb, "Index bitmap too small (0x%llx) "
                                        "for index allocation (0x%llx).",
                                        bvi->i_size << 3, vi->i_size);
                        goto unm_err_out;
                }
skip_large_dir_stuff:
                /* Everyone gets read and scan permissions. */
                vi->i_mode |= S_IRUGO | S_IXUGO;
                /* If not read-only, set write permissions. */
                if (!IS_RDONLY(vi))
                        vi->i_mode |= S_IWUGO;
                /*
                 * Apply the directory permissions mask set in the mount
                 * options.
                 */
                vi->i_mode &= ~vol->dmask;
                /* Setup the operations for this inode. */
                vi->i_op = &ntfs_dir_inode_ops;
                vi->i_fop = &ntfs_dir_ops;
                vi->i_mapping->a_ops = &ntfs_aops;
        } else {
                /* It is a file. */
                reinit_attr_search_ctx(ctx);

                /* Setup the data attribute, even if not present. */
                ni->type = AT_DATA;
                ni->name = NULL;
                ni->name_len = 0;

                /* Find first extent of the unnamed data attribute. */
                if (!lookup_attr(AT_DATA, NULL, 0, 0, 0, NULL, 0, ctx)) {
                        vi->i_size = ni->initialized_size =
                                        ni->allocated_size = 0LL;
                        /*
                         * FILE_Secure does not have an unnamed $DATA
                         * attribute, so we special case it here.
                         */
                        if (vi->i_ino == FILE_Secure)
                                goto no_data_attr_special_case;
                        /*
                         * Most if not all the system files in the $Extend
                         * system directory do not have unnamed data
                         * attributes so we need to check if the parent
                         * directory of the file is FILE_Extend and if it is
                         * ignore this error. To do this we need to get the
                         * name of this inode from the mft record as the name
                         * contains the back reference to the parent directory.
                         */
                        if (ntfs_is_extended_system_file(ctx) > 0)
                                goto no_data_attr_special_case;
                        // FIXME: File is corrupt! Hot-fix with empty data
                        // attribute if recovery option is set.
                        ntfs_error(vi->i_sb, "$DATA attribute is "
                                        "missing.");
                        goto unm_err_out;
                }
                /* Setup the state. */
                if (ctx->attr->non_resident) {
                        NInoSetNonResident(ni);
                        if (ctx->attr->flags & ATTR_COMPRESSION_MASK) {
                                NInoSetCompressed(ni);
                                if (vol->cluster_size > 4096) {
                                        ntfs_error(vi->i_sb, "Found "
                                                "compressed data but "
                                                "compression is disabled due "
                                                "to cluster size (%i) > 4kiB.",
                                                vol->cluster_size);
                                        goto unm_err_out;
                                }
                                if ((ctx->attr->flags & ATTR_COMPRESSION_MASK)
                                                != ATTR_IS_COMPRESSED) {
                                        ntfs_error(vi->i_sb, "Found "
                                                "unknown compression method or "
                                                "corrupt file.");
                                        goto unm_err_out;
                                }
                                ni->itype.compressed.block_clusters = 1U <<
                                                ctx->attr->data.non_resident.
                                                compression_unit;
                                if (ctx->attr->data.non_resident.
                                                compression_unit != 4) {
                                        ntfs_error(vi->i_sb, "Found "
                                                "nonstandard compression unit "
                                                "(%u instead of 4). Cannot "
                                                "handle this. This might "
                                                "indicate corruption so you "
                                                "should run chkdsk.",
                                                ctx->attr->data.non_resident.
                                                compression_unit);
                                        err = -EOPNOTSUPP;
                                        goto unm_err_out;
                                }
                                ni->itype.compressed.block_size = 1U << (
                                                ctx->attr->data.non_resident.
                                                compression_unit +
                                                vol->cluster_size_bits);
                                ni->itype.compressed.block_size_bits = ffs(
                                        ni->itype.compressed.block_size) - 1;
                        }
                        if (ctx->attr->flags & ATTR_IS_ENCRYPTED) {
                                if (ctx->attr->flags & ATTR_COMPRESSION_MASK) {
                                        ntfs_error(vi->i_sb, "Found encrypted "
                                                        "and compressed data.");
                                        goto unm_err_out;
                                }
                                NInoSetEncrypted(ni);
                        }
                        if (ctx->attr->flags & ATTR_IS_SPARSE)
                                NInoSetSparse(ni);
                        if (ctx->attr->data.non_resident.lowest_vcn) {
                                ntfs_error(vi->i_sb, "First extent of $DATA "
                                                "attribute has non zero "
                                                "lowest_vcn. Inode is corrupt. "
                                                "You should run chkdsk.");
                                goto unm_err_out;
                        }
                        /* Setup all the sizes. */
                        vi->i_size = sle64_to_cpu(
                                        ctx->attr->data.non_resident.data_size);
                        ni->initialized_size = sle64_to_cpu(
                                        ctx->attr->data.non_resident.
                                        initialized_size);
                        ni->allocated_size = sle64_to_cpu(
                                        ctx->attr->data.non_resident.
                                        allocated_size);
                        if (NInoCompressed(ni)) {
                                ni->itype.compressed.size = sle64_to_cpu(
                                                ctx->attr->data.non_resident.
                                                compressed_size);
                        }
                } else { /* Resident attribute. */
                        /*
                         * Make all sizes equal for simplicity in read code
                         * paths. FIXME: Need to keep this in mind when
                         * converting to non-resident attribute in write code
                         * path. (Probably only affects truncate().)
                         */
                        vi->i_size = ni->initialized_size = ni->allocated_size =
                                        le32_to_cpu(
                                        ctx->attr->data.resident.value_length);
                }
no_data_attr_special_case:
                /* We are done with the mft record, so we release it. */
                put_attr_search_ctx(ctx);
                unmap_mft_record(ni);
                m = NULL;
                ctx = NULL;
                /* Everyone gets all permissions. */
                vi->i_mode |= S_IRWXUGO;
                /* If read-only, noone gets write permissions. */
                if (IS_RDONLY(vi))
                        vi->i_mode &= ~S_IWUGO;
                /* Apply the file permissions mask set in the mount options. */
                vi->i_mode &= ~vol->fmask;
                /* Setup the operations for this inode. */
                vi->i_op = &ntfs_file_inode_ops;
                vi->i_fop = &ntfs_file_ops;
                vi->i_mapping->a_ops = &ntfs_aops;
        }
        /*
         * The number of 512-byte blocks used on disk (for stat). This is in so
         * far inaccurate as it doesn't account for any named streams or other
         * special non-resident attributes, but that is how Windows works, too,
         * so we are at least consistent with Windows, if not entirely
         * consistent with the Linux Way. Doing it the Linux Way would cause a
         * significant slowdown as it would involve iterating over all
         * attributes in the mft record and adding the allocated/compressed
         * sizes of all non-resident attributes present to give us the Linux
         * correct size that should go into i_blocks (after division by 512).
         */
        if (S_ISDIR(vi->i_mode) || !NInoCompressed(ni))
                vi->i_blocks = ni->allocated_size >> 9;
        else
                vi->i_blocks = ni->itype.compressed.size >> 9;

        ntfs_debug("Done.");
        return 0;

unm_err_out:
        if (!err)
                err = -EIO;
        if (ctx)
                put_attr_search_ctx(ctx);
        if (m)
                unmap_mft_record(ni);
err_out:
        ntfs_error(vi->i_sb, "Failed with error code %i. Marking inode 0x%lx "
                        "as bad.", -err, vi->i_ino);
        make_bad_inode(vi);
        return err;
}

/**
 * ntfs_read_locked_attr_inode - read an attribute inode from its base inode
 * @base_vi:    base inode
 * @vi:         attribute inode to read
 *
 * ntfs_read_locked_attr_inode() is called from the ntfs_attr_iget() to read
 * the attribute inode described by @vi into memory from the base mft record
 * described by @base_ni.
 *
 * ntfs_read_locked_attr_inode() maps, pins and locks the base inode for
 * reading and looks up the attribute described by @vi before setting up the
 * necessary fields in @vi as well as initializing the ntfs inode.
 *
 * Q: What locks are held when the function is called?
 * A: i_state has I_LOCK set, hence the inode is locked, also
 *    i_count is set to 1, so it is not going to go away
 */
static int ntfs_read_locked_attr_inode(struct inode *base_vi, struct inode *vi)
{
        ntfs_volume *vol = NTFS_SB(vi->i_sb);
        ntfs_inode *ni, *base_ni;
        MFT_RECORD *m;
        attr_search_context *ctx;
        int err = 0;

        ntfs_debug("Entering for i_ino 0x%lx.", vi->i_ino);

        ntfs_init_big_inode(vi);

        ni      = NTFS_I(vi);
        base_ni = NTFS_I(base_vi);

        /* Just mirror the values from the base inode. */
        vi->i_blksize   = base_vi->i_blksize;
        vi->i_version   = base_vi->i_version;
        vi->i_uid       = base_vi->i_uid;
        vi->i_gid       = base_vi->i_gid;
        vi->i_nlink     = base_vi->i_nlink;
        vi->i_mtime     = base_vi->i_mtime;
        vi->i_ctime     = base_vi->i_ctime;
        vi->i_atime     = base_vi->i_atime;
        vi->i_generation = ni->seq_no = base_ni->seq_no;

        /* Set inode type to zero but preserve permissions. */
        vi->i_mode      = base_vi->i_mode & ~S_IFMT;

        m = map_mft_record(base_ni);
        if (IS_ERR(m)) {
                err = PTR_ERR(m);
                goto err_out;
        }
        ctx = get_attr_search_ctx(base_ni, m);
        if (!ctx) {
                err = -ENOMEM;
                goto unm_err_out;
        }

        /* Find the attribute. */
        if (!lookup_attr(ni->type, ni->name, ni->name_len, IGNORE_CASE, 0,
                        NULL, 0, ctx))
                goto unm_err_out;

        if (!ctx->attr->non_resident) {
                if (NInoMstProtected(ni) || ctx->attr->flags) {
                        ntfs_error(vi->i_sb, "Found mst protected attribute "
                                        "or attribute with non-zero flags but "
                                        "the attribute is resident (mft_no "
                                        "0x%lx, type 0x%x, name_len %i). "
                                        "Please report you saw this message "
                                        "to linux-ntfs-dev@lists."
                                        "sourceforge.net",
                                        vi->i_ino, ni->type, ni->name_len);
                        goto unm_err_out;
                }
                /*
                 * Resident attribute. Make all sizes equal for simplicity in
                 * read code paths.
                 */
                vi->i_size = ni->initialized_size = ni->allocated_size =
                        le32_to_cpu(ctx->attr->data.resident.value_length);
        } else {
                NInoSetNonResident(ni);
                if (ctx->attr->flags & ATTR_COMPRESSION_MASK) {
                        if (NInoMstProtected(ni)) {
                                ntfs_error(vi->i_sb, "Found mst protected "
                                                "attribute but the attribute "
                                                "is compressed (mft_no 0x%lx, "
                                                "type 0x%x, name_len %i). "
                                                "Please report you saw this "
                                                "message to linux-ntfs-dev@"
                                                "lists.sourceforge.net",
                                                vi->i_ino, ni->type,
                                                ni->name_len);
                                goto unm_err_out;
                        }
                        NInoSetCompressed(ni);
                        if ((ni->type != AT_DATA) || (ni->type == AT_DATA &&
                                        ni->name_len)) {
                                ntfs_error(vi->i_sb, "Found compressed non-"
                                                "data or named data attribute "
                                                "(mft_no 0x%lx, type 0x%x, "
                                                "name_len %i). Please report "
                                                "you saw this message to "
                                                "linux-ntfs-dev@lists."
                                                "sourceforge.net",
                                                vi->i_ino, ni->type,
                                                ni->name_len);
                                goto unm_err_out;
                        }
                        if (vol->cluster_size > 4096) {
                                ntfs_error(vi->i_sb, "Found "
                                        "compressed attribute but "
                                        "compression is disabled due "
                                        "to cluster size (%i) > 4kiB.",
                                        vol->cluster_size);
                                goto unm_err_out;
                        }
                        if ((ctx->attr->flags & ATTR_COMPRESSION_MASK)
                                        != ATTR_IS_COMPRESSED) {
                                ntfs_error(vi->i_sb, "Found unknown "
                                                "compression method or "
                                                "corrupt file.");
                                goto unm_err_out;
                        }
                        ni->itype.compressed.block_clusters = 1U <<
                                        ctx->attr->data.non_resident.
                                        compression_unit;
                        if (ctx->attr->data.non_resident.compression_unit != 4) {
                                ntfs_error(vi->i_sb, "Found "
                                        "nonstandard compression unit "
                                        "(%u instead of 4). Cannot "
                                        "handle this. This might "
                                        "indicate corruption so you "
                                        "should run chkdsk.",
                                        ctx->attr->data.non_resident.
                                        compression_unit);
                                err = -EOPNOTSUPP;
                                goto unm_err_out;
                        }
                        ni->itype.compressed.block_size = 1U << (
                                        ctx->attr->data.non_resident.
                                        compression_unit +
                                        vol->cluster_size_bits);
                        ni->itype.compressed.block_size_bits = ffs(
                                ni->itype.compressed.block_size) - 1;
                }
                if (ctx->attr->flags & ATTR_IS_ENCRYPTED) {
                        if (ctx->attr->flags & ATTR_COMPRESSION_MASK) {
                                ntfs_error(vi->i_sb, "Found encrypted "
                                                "and compressed data.");
                                goto unm_err_out;
                        }
                        if (NInoMstProtected(ni)) {
                                ntfs_error(vi->i_sb, "Found mst protected "
                                                "attribute but the attribute "
                                                "is encrypted (mft_no 0x%lx, "
                                                "type 0x%x, name_len %i). "
                                                "Please report you saw this "
                                                "message to linux-ntfs-dev@"
                                                "lists.sourceforge.net",
                                                vi->i_ino, ni->type,
                                                ni->name_len);
                                goto unm_err_out;
                        }
                        NInoSetEncrypted(ni);
                }
                if (ctx->attr->flags & ATTR_IS_SPARSE) {
                        if (NInoMstProtected(ni)) {
                                ntfs_error(vi->i_sb, "Found mst protected "
                                                "attribute but the attribute "
                                                "is sparse (mft_no 0x%lx, "
                                                "type 0x%x, name_len %i). "
                                                "Please report you saw this "
                                                "message to linux-ntfs-dev@"
                                                "lists.sourceforge.net",
                                                vi->i_ino, ni->type,
                                                ni->name_len);
                                goto unm_err_out;
                        }
                        NInoSetSparse(ni);
                }
                if (ctx->attr->data.non_resident.lowest_vcn) {
                        ntfs_error(vi->i_sb, "First extent of attribute has "
                                        "non-zero lowest_vcn. Inode is "
                                        "corrupt. You should run chkdsk.");
                        goto unm_err_out;
                }
                /* Setup all the sizes. */
                vi->i_size = sle64_to_cpu(
                                ctx->attr->data.non_resident.data_size);
                ni->initialized_size = sle64_to_cpu(
                                ctx->attr->data.non_resident.initialized_size);
                ni->allocated_size = sle64_to_cpu(
                                ctx->attr->data.non_resident.allocated_size);
                if (NInoCompressed(ni)) {
                        ni->itype.compressed.size = sle64_to_cpu(
                                        ctx->attr->data.non_resident.
                                        compressed_size);
                }
        }

        /* Setup the operations for this attribute inode. */
        vi->i_op = NULL;
        vi->i_fop = NULL;
        vi->i_mapping->a_ops = &ntfs_aops;

        if (!NInoCompressed(ni))
                vi->i_blocks = ni->allocated_size >> 9;
        else
                vi->i_blocks = ni->itype.compressed.size >> 9;

        /*
         * Make sure the base inode doesn't go away and attach it to the
         * attribute inode.
         */
        igrab(base_vi);
        ni->ext.base_ntfs_ino = base_ni;
        ni->nr_extents = -1;

        put_attr_search_ctx(ctx);
        unmap_mft_record(base_ni);

        ntfs_debug("Done.");
        return 0;

unm_err_out:
        if (!err)
                err = -EIO;
        if (ctx)
                put_attr_search_ctx(ctx);
        unmap_mft_record(base_ni);
err_out:
        ntfs_error(vi->i_sb, "Failed with error code %i while reading "
                        "attribute inode (mft_no 0x%lx, type 0x%x, name_len "
                        "%i.", -err, vi->i_ino, ni->type, ni->name_len);
        make_bad_inode(vi);
        return err;
}

/**
 * ntfs_read_inode_mount - special read_inode for mount time use only
 * @vi:         inode to read
 *
 * Read inode FILE_MFT at mount time, only called with super_block lock
 * held from within the read_super() code path.
 *
 * This function exists because when it is called the page cache for $MFT/$DATA
 * is not initialized and hence we cannot get at the contents of mft records
 * by calling map_mft_record*().
 *
 * Further it needs to cope with the circular references problem, i.e. can't
 * load any attributes other than $ATTRIBUTE_LIST until $DATA is loaded, because
 * we don't know where the other extent mft records are yet and again, because
 * we cannot call map_mft_record*() yet. Obviously this applies only when an
 * attribute list is actually present in $MFT inode.
 *
 * We solve these problems by starting with the $DATA attribute before anything
 * else and iterating using lookup_attr($DATA) over all extents. As each extent
 * is found, we decompress_mapping_pairs() including the implied
 * merge_run_lists(). Each step of the iteration necessarily provides
 * sufficient information for the next step to complete.
 *
 * This should work but there are two possible pit falls (see inline comments
 * below), but only time will tell if they are real pits or just smoke...
 */
int ntfs_read_inode_mount(struct inode *vi)
{
        VCN next_vcn, last_vcn, highest_vcn;
        s64 block;
        struct super_block *sb = vi->i_sb;
        ntfs_volume *vol = NTFS_SB(sb);
        struct buffer_head *bh;
        ntfs_inode *ni;
        MFT_RECORD *m = NULL;
        ATTR_RECORD *attr;
        attr_search_context *ctx;
        unsigned int i, nr_blocks;
        int err;

        ntfs_debug("Entering.");

        /* Initialize the ntfs specific part of @vi. */
        ntfs_init_big_inode(vi);

        ni = NTFS_I(vi);

        /* Setup the data attribute. It is special as it is mst protected. */
        NInoSetNonResident(ni);
        NInoSetMstProtected(ni);
        ni->type = AT_DATA;
        ni->name = NULL;
        ni->name_len = 0;

        /*
         * This sets up our little cheat allowing us to reuse the async io
         * completion handler for directories.
         */
        ni->itype.index.block_size = vol->mft_record_size;
        ni->itype.index.block_size_bits = vol->mft_record_size_bits;

        /* Very important! Needed to be able to call map_mft_record*(). */
        vol->mft_ino = vi;

        /* Allocate enough memory to read the first mft record. */
        if (vol->mft_record_size > 64 * 1024) {
                ntfs_error(sb, "Unsupported mft record size %i (max 64kiB).",
                                vol->mft_record_size);
                goto err_out;
        }
        i = vol->mft_record_size;
        if (i < sb->s_blocksize)
                i = sb->s_blocksize;
        m = (MFT_RECORD*)ntfs_malloc_nofs(i);
        if (!m) {
                ntfs_error(sb, "Failed to allocate buffer for $MFT record 0.");
                goto err_out;
        }

        /* Determine the first block of the $MFT/$DATA attribute. */
        block = vol->mft_lcn << vol->cluster_size_bits >>
                        sb->s_blocksize_bits;
        nr_blocks = vol->mft_record_size >> sb->s_blocksize_bits;
        if (!nr_blocks)
                nr_blocks = 1;

        /* Load $MFT/$DATA's first mft record. */
        for (i = 0; i < nr_blocks; i++) {
                bh = sb_bread(sb, block++);
                if (!bh) {
                        ntfs_error(sb, "Device read failed.");
                        goto err_out;
                }
                memcpy((char*)m + (i << sb->s_blocksize_bits), bh->b_data,
                                sb->s_blocksize);
                brelse(bh);
        }

        /* Apply the mst fixups. */
        if (post_read_mst_fixup((NTFS_RECORD*)m, vol->mft_record_size)) {
                /* FIXME: Try to use the $MFTMirr now. */
                ntfs_error(sb, "MST fixup failed. $MFT is corrupt.");
                goto err_out;
        }

        /* Need this to sanity check attribute list references to $MFT. */
        vi->i_generation = ni->seq_no = le16_to_cpu(m->sequence_number);

        /* Provides readpage() and sync_page() for map_mft_record(). */
        vi->i_mapping->a_ops = &ntfs_mft_aops;

        ctx = get_attr_search_ctx(ni, m);
        if (!ctx) {
                err = -ENOMEM;
                goto err_out;
        }

        /* Find the attribute list attribute if present. */
        if (lookup_attr(AT_ATTRIBUTE_LIST, NULL, 0, 0, 0, NULL, 0, ctx)) {
                ATTR_LIST_ENTRY *al_entry, *next_al_entry;
                u8 *al_end;

                ntfs_debug("Attribute list attribute found in $MFT.");
                NInoSetAttrList(ni);
                if (ctx->attr->flags & ATTR_IS_ENCRYPTED ||
                                ctx->attr->flags & ATTR_COMPRESSION_MASK ||
                                ctx->attr->flags & ATTR_IS_SPARSE) {
                        ntfs_error(sb, "Attribute list attribute is "
                                        "compressed/encrypted/sparse. Not "
                                        "allowed. $MFT is corrupt. You should "
                                        "run chkdsk.");
                        goto put_err_out;
                }
                /* Now allocate memory for the attribute list. */
                ni->attr_list_size = (u32)attribute_value_length(ctx->attr);
                ni->attr_list = ntfs_malloc_nofs(ni->attr_list_size);
                if (!ni->attr_list) {
                        ntfs_error(sb, "Not enough memory to allocate buffer "
                                        "for attribute list.");
                        goto put_err_out;
                }
                if (ctx->attr->non_resident) {
                        NInoSetAttrListNonResident(ni);
                        if (ctx->attr->data.non_resident.lowest_vcn) {
                                ntfs_error(sb, "Attribute list has non zero "
                                                "lowest_vcn. $MFT is corrupt. "
                                                "You should run chkdsk.");
                                goto put_err_out;
                        }
                        /* Setup the run list. */
                        ni->attr_list_rl.rl = decompress_mapping_pairs(vol,
                                        ctx->attr, NULL);
                        if (IS_ERR(ni->attr_list_rl.rl)) {
                                err = PTR_ERR(ni->attr_list_rl.rl);
                                ni->attr_list_rl.rl = NULL;
                                ntfs_error(sb, "Mapping pairs decompression "
                                                "failed with error code %i.",
                                                -err);
                                goto put_err_out;
                        }
                        /* Now load the attribute list. */
                        if ((err = load_attribute_list(vol, &ni->attr_list_rl,
                                        ni->attr_list, ni->attr_list_size,
                                        sle64_to_cpu(ctx->attr->data.
                                        non_resident.initialized_size)))) {
                                ntfs_error(sb, "Failed to load attribute list "
                                                "attribute with error code %i.",
                                                -err);
                                goto put_err_out;
                        }
                } else /* if (!ctx.attr->non_resident) */ {
                        if ((u8*)ctx->attr + le16_to_cpu(
                                        ctx->attr->data.resident.value_offset) +
                                        le32_to_cpu(
                                        ctx->attr->data.resident.value_length) >
                                        (u8*)ctx->mrec + vol->mft_record_size) {
                                ntfs_error(sb, "Corrupt attribute list "
                                                "attribute.");
                                goto put_err_out;
                        }
                        /* Now copy the attribute list. */
                        memcpy(ni->attr_list, (u8*)ctx->attr + le16_to_cpu(
                                        ctx->attr->data.resident.value_offset),
                                        le32_to_cpu(
                                        ctx->attr->data.resident.value_length));
                }
                /* The attribute list is now setup in memory. */
                /*
                 * FIXME: I don't know if this case is actually possible.
                 * According to logic it is not possible but I have seen too
                 * many weird things in MS software to rely on logic... Thus we
                 * perform a manual search and make sure the first $MFT/$DATA
                 * extent is in the base inode. If it is not we abort with an
                 * error and if we ever see a report of this error we will need
                 * to do some magic in order to have the necessary mft record
                 * loaded and in the right place in the page cache. But
                 * hopefully logic will prevail and this never happens...
                 */
                al_entry = (ATTR_LIST_ENTRY*)ni->attr_list;
                al_end = (u8*)al_entry + ni->attr_list_size;
                for (;; al_entry = next_al_entry) {
                        /* Out of bounds check. */
                        if ((u8*)al_entry < ni->attr_list ||
                                        (u8*)al_entry > al_end)
                                goto em_put_err_out;
                        /* Catch the end of the attribute list. */
                        if ((u8*)al_entry == al_end)
                                goto em_put_err_out;
                        if (!al_entry->length)
                                goto em_put_err_out;
                        if ((u8*)al_entry + 6 > al_end || (u8*)al_entry +
                                        le16_to_cpu(al_entry->length) > al_end)
                                goto em_put_err_out;
                        next_al_entry = (ATTR_LIST_ENTRY*)((u8*)al_entry +
                                        le16_to_cpu(al_entry->length));
                        if (le32_to_cpu(al_entry->type) >
                                        const_le32_to_cpu(AT_DATA))
                                goto em_put_err_out;
                        if (AT_DATA != al_entry->type)
                                continue;
                        /* We want an unnamed attribute. */
                        if (al_entry->name_length)
                                goto em_put_err_out;
                        /* Want the first entry, i.e. lowest_vcn == 0. */
                        if (al_entry->lowest_vcn)
                                goto em_put_err_out;
                        /* First entry has to be in the base mft record. */
                        if (MREF_LE(al_entry->mft_reference) != vi->i_ino) {
                                /* MFT references do not match, logic fails. */
                                ntfs_error(sb, "BUG: The first $DATA extent "
                                                "of $MFT is not in the base "
                                                "mft record. Please report "
                                                "you saw this message to "
                                                "linux-ntfs-dev@lists."
                                                "sourceforge.net");
                                goto put_err_out;
                        } else {
                                /* Sequence numbers must match. */
                                if (MSEQNO_LE(al_entry->mft_reference) !=
                                                ni->seq_no)
                                        goto em_put_err_out;
                                /* Got it. All is ok. We can stop now. */
                                break;
                        }
                }
        }

        reinit_attr_search_ctx(ctx);

        /* Now load all attribute extents. */
        attr = NULL;
        next_vcn = last_vcn = highest_vcn = 0;
        while (lookup_attr(AT_DATA, NULL, 0, 0, next_vcn, NULL, 0, ctx)) {
                run_list_element *nrl;

                /* Cache the current attribute. */
                attr = ctx->attr;
                /* $MFT must be non-resident. */
                if (!attr->non_resident) {
                        ntfs_error(sb, "$MFT must be non-resident but a "
                                        "resident extent was found. $MFT is "
                                        "corrupt. Run chkdsk.");
                        goto put_err_out;
                }
                /* $MFT must be uncompressed and unencrypted. */
                if (attr->flags & ATTR_COMPRESSION_MASK ||
                                attr->flags & ATTR_IS_ENCRYPTED ||
                                attr->flags & ATTR_IS_SPARSE) {
                        ntfs_error(sb, "$MFT must be uncompressed, "
                                        "non-sparse, and unencrypted but a "
                                        "compressed/sparse/encrypted extent "
                                        "was found. $MFT is corrupt. Run "
                                        "chkdsk.");
                        goto put_err_out;
                }
                /*
                 * Decompress the mapping pairs array of this extent and merge
                 * the result into the existing run list. No need for locking
                 * as we have exclusive access to the inode at this time and we
                 * are a mount in progress task, too.
                 */
                nrl = decompress_mapping_pairs(vol, attr, ni->run_list.rl);
                if (IS_ERR(nrl)) {
                        ntfs_error(sb, "decompress_mapping_pairs() failed with "
                                        "error code %ld. $MFT is corrupt.",
                                        PTR_ERR(nrl));
                        goto put_err_out;
                }
                ni->run_list.rl = nrl;

                /* Are we in the first extent? */
                if (!next_vcn) {
                        u64 ll;

                        if (attr->data.non_resident.lowest_vcn) {
                                ntfs_error(sb, "First extent of $DATA "
                                                "attribute has non zero "
                                                "lowest_vcn. $MFT is corrupt. "
                                                "You should run chkdsk.");
                                goto put_err_out;
                        }
                        /* Get the last vcn in the $DATA attribute. */
                        last_vcn = sle64_to_cpu(
                                        attr->data.non_resident.allocated_size)
                                        >> vol->cluster_size_bits;
                        /* Fill in the inode size. */
                        vi->i_size = sle64_to_cpu(
                                        attr->data.non_resident.data_size);
                        ni->initialized_size = sle64_to_cpu(attr->data.
                                        non_resident.initialized_size);
                        ni->allocated_size = sle64_to_cpu(
                                        attr->data.non_resident.allocated_size);
                        /* Set the number of mft records. */
                        ll = vi->i_size >> vol->mft_record_size_bits;
                        /*
                         * Verify the number of mft records does not exceed
                         * 2^32 - 1.
                         */
                        if (ll >= (1ULL << 32)) {
                                ntfs_error(sb, "$MFT is too big! Aborting.");
                                goto put_err_out;
                        }
                        vol->nr_mft_records = ll;
                        /*
                         * We have got the first extent of the run_list for
                         * $MFT which means it is now relatively safe to call
                         * the normal ntfs_read_inode() function.
                         * Complete reading the inode, this will actually
                         * re-read the mft record for $MFT, this time entering
                         * it into the page cache with which we complete the
                         * kick start of the volume. It should be safe to do
                         * this now as the first extent of $MFT/$DATA is
                         * already known and we would hope that we don't need
                         * further extents in order to find the other
                         * attributes belonging to $MFT. Only time will tell if
                         * this is really the case. If not we will have to play
                         * magic at this point, possibly duplicating a lot of
                         * ntfs_read_inode() at this point. We will need to
                         * ensure we do enough of its work to be able to call
                         * ntfs_read_inode() on extents of $MFT/$DATA. But lets
                         * hope this never happens...
                         */
                        ntfs_read_locked_inode(vi);
                        if (is_bad_inode(vi)) {
                                ntfs_error(sb, "ntfs_read_inode() of $MFT "
                                                "failed. BUG or corrupt $MFT. "
                                                "Run chkdsk and if no errors "
                                                "are found, please report you "
                                                "saw this message to "
                                                "linux-ntfs-dev@lists."
                                                "sourceforge.net");
                                put_attr_search_ctx(ctx);
                                /* Revert to the safe super operations. */
                                ntfs_free(m);
                                return -1;
                        }
                        /*
                         * Re-initialize some specifics about $MFT's inode as
                         * ntfs_read_inode() will have set up the default ones.
                         */
                        /* Set uid and gid to root. */
                        vi->i_uid = vi->i_gid = 0;
                        /* Regular file. No access for anyone. */
                        vi->i_mode = S_IFREG;
                        /* No VFS initiated operations allowed for $MFT. */
                        vi->i_op = &ntfs_empty_inode_ops;
                        vi->i_fop = &ntfs_empty_file_ops;
                        /* Put back our special address space operations. */
                        vi->i_mapping->a_ops = &ntfs_mft_aops;
                }

                /* Get the lowest vcn for the next extent. */
                highest_vcn = sle64_to_cpu(attr->data.non_resident.highest_vcn);
                next_vcn = highest_vcn + 1;

                /* Only one extent or error, which we catch below. */
                if (next_vcn <= 0)
                        break;

                /* Avoid endless loops due to corruption. */
                if (next_vcn < sle64_to_cpu(
                                attr->data.non_resident.lowest_vcn)) {
                        ntfs_error(sb, "$MFT has corrupt attribute list "
                                        "attribute. Run chkdsk.");
                        goto put_err_out;
                }
        }
        if (!attr) {
                ntfs_error(sb, "$MFT/$DATA attribute not found. $MFT is "
                                "corrupt. Run chkdsk.");
                goto put_err_out;
        }
        if (highest_vcn && highest_vcn != last_vcn - 1) {
                ntfs_error(sb, "Failed to load the complete run list "
                                "for $MFT/$DATA. Driver bug or "
                                "corrupt $MFT. Run chkdsk.");
                ntfs_debug("highest_vcn = 0x%llx, last_vcn - 1 = 0x%llx",
                                (unsigned long long)highest_vcn,
                                (unsigned long long)last_vcn - 1);
                goto put_err_out;
        }
        put_attr_search_ctx(ctx);
        ntfs_debug("Done.");
        ntfs_free(m);
        return 0;

em_put_err_out:
        ntfs_error(sb, "Couldn't find first extent of $DATA attribute in "
                        "attribute list. $MFT is corrupt. Run chkdsk.");
put_err_out:
        put_attr_search_ctx(ctx);
err_out:
        ntfs_error(sb, "Failed. Marking inode as bad.");
        make_bad_inode(vi);
        ntfs_free(m);
        return -1;
}

/**
 * ntfs_commit_inode - write out a dirty inode
 * @ni:         inode to write out
 *
 */
int ntfs_commit_inode(ntfs_inode *ni)
{
        ntfs_debug("Entering for inode 0x%lx.", ni->mft_no);
        NInoClearDirty(ni);
        return 0;
}

/**
 * ntfs_put_inode - handler for when the inode reference count is decremented
 * @vi:         vfs inode
 *
 * The VFS calls ntfs_put_inode() every time the inode reference count (i_count)
 * is about to be decremented (but before the decrement itself.
 *
 * If the inode @vi is a directory with a single reference, we need to put the
 * attribute inode for the directory index bitmap, if it is present, otherwise
 * the directory inode would remain pinned for ever (or rather until umount()
 * time.
 */
void ntfs_put_inode(struct inode *vi)
{
        if (S_ISDIR(vi->i_mode) && (atomic_read(&vi->i_count) == 2)) {
                ntfs_inode *ni;

                ni = NTFS_I(vi);
                if (NInoIndexAllocPresent(ni) && ni->itype.index.bmp_ino) {
                        iput(ni->itype.index.bmp_ino);
                        ni->itype.index.bmp_ino = NULL;
                }
        }
        return;
}

void __ntfs_clear_inode(ntfs_inode *ni)
{
        int err;

        ntfs_debug("Entering for inode 0x%lx.", ni->mft_no);
        if (NInoDirty(ni)) {
                err = ntfs_commit_inode(ni);
                if (err) {
                        ntfs_error(ni->vol->sb, "Failed to commit dirty "
                                        "inode synchronously.");
                        // FIXME: Do something!!!
                }
        }
        /* Synchronize with ntfs_commit_inode(). */
        down(&ni->mrec_lock);
        up(&ni->mrec_lock);
        if (NInoDirty(ni)) {
                ntfs_error(ni->vol->sb, "Failed to commit dirty inode "
                                "asynchronously.");
                // FIXME: Do something!!!
        }
        /* No need to lock at this stage as no one else has a reference. */
        if (ni->nr_extents > 0) {
                int i;

                // FIXME: Handle dirty case for each extent inode!
                for (i = 0; i < ni->nr_extents; i++)
                        ntfs_clear_extent_inode(ni->ext.extent_ntfs_inos[i]);
                kfree(ni->ext.extent_ntfs_inos);
        }
        /* Free all alocated memory. */
        down_write(&ni->run_list.lock);
        if (ni->run_list.rl) {
                ntfs_free(ni->run_list.rl);
                ni->run_list.rl = NULL;
        }
        up_write(&ni->run_list.lock);

        if (ni->attr_list) {
                ntfs_free(ni->attr_list);
                ni->attr_list = NULL;
        }

        down_write(&ni->attr_list_rl.lock);
        if (ni->attr_list_rl.rl) {
                ntfs_free(ni->attr_list_rl.rl);
                ni->attr_list_rl.rl = NULL;
        }
        up_write(&ni->attr_list_rl.lock);

        if (ni->name_len && ni->name != I30) {
                /* Catch bugs... */
                BUG_ON(!ni->name);
                kfree(ni->name);
        }
}

void ntfs_clear_extent_inode(ntfs_inode *ni)
{
        __ntfs_clear_inode(ni);

        /* Bye, bye... */
        ntfs_destroy_extent_inode(ni);
}

/**
 * ntfs_clear_big_inode - clean up the ntfs specific part of an inode
 * @vi:         vfs inode pending annihilation
 *
 * When the VFS is going to remove an inode from memory, ntfs_clear_big_inode()
 * is called, which deallocates all memory belonging to the NTFS specific part
 * of the inode and returns.
 *
 * If the MFT record is dirty, we commit it before doing anything else.
 */
void ntfs_clear_big_inode(struct inode *vi)
{
        ntfs_inode *ni = NTFS_I(vi);

        __ntfs_clear_inode(ni);

        if (NInoAttr(ni)) {
                /* Release the base inode if we are holding it. */
                if (ni->nr_extents == -1) {
                        iput(VFS_I(ni->ext.base_ntfs_ino));
                        ni->nr_extents = 0;
                        ni->ext.base_ntfs_ino = NULL;
                }
        }
        return;
}

/**
 * ntfs_show_options - show mount options in /proc/mounts
 * @sf:         seq_file in which to write our mount options
 * @mnt:        vfs mount whose mount options to display
 *
 * Called by the VFS once for each mounted ntfs volume when someone reads
 * /proc/mounts in order to display the NTFS specific mount options of each
 * mount. The mount options of the vfs mount @mnt are written to the seq file
 * @sf and success is returned.
 */
int ntfs_show_options(struct seq_file *sf, struct vfsmount *mnt)
{
        ntfs_volume *vol = NTFS_SB(mnt->mnt_sb);
        int i;

        seq_printf(sf, ",uid=%i", vol->uid);
        seq_printf(sf, ",gid=%i", vol->gid);
        if (vol->fmask == vol->dmask)
                seq_printf(sf, ",umask=0%o", vol->fmask);
        else {
                seq_printf(sf, ",fmask=0%o", vol->fmask);
                seq_printf(sf, ",dmask=0%o", vol->dmask);
        }
        seq_printf(sf, ",nls=%s", vol->nls_map->charset);
        if (NVolCaseSensitive(vol))
                seq_printf(sf, ",case_sensitive");
        if (NVolShowSystemFiles(vol))
                seq_printf(sf, ",show_sys_files");
        for (i = 0; on_errors_arr[i].val; i++) {
                if (on_errors_arr[i].val & vol->on_errors)
                        seq_printf(sf, ",errors=%s", on_errors_arr[i].str);
        }
        seq_printf(sf, ",mft_zone_multiplier=%i", vol->mft_zone_multiplier);
        return 0;
}

#ifdef NTFS_RW

/**
 * ntfs_truncate - called when the i_size of an ntfs inode is changed
 * @vi:         inode for which the i_size was changed
 *
 * We don't support i_size changes yet.
 *
 * Called with ->i_sem held.
 */
void ntfs_truncate(struct inode *vi)
{
        // TODO: Implement...
        ntfs_warning(vi->i_sb, "Eeek: i_size may have changed! If you see "
                        "this right after a message from "
                        "ntfs_{prepare,commit}_{,nonresident_}write() then "
                        "just ignore it. Otherwise it is bad news.");
        // TODO: reset i_size now!
        return;
}

/**
 * ntfs_setattr - called from notify_change() when an attribute is being changed
 * @dentry:     dentry whose attributes to change
 * @attr:       structure describing the attributes and the changes
 *
 * We have to trap VFS attempts to truncate the file described by @dentry as
 * soon as possible, because we do not implement changes in i_size yet. So we
 * abort all i_size changes here.
 *
 * Called with ->i_sem held.
 *
 * Basically this is a copy of generic notify_change() and inode_setattr()
 * functionality, except we intercept and abort changes in i_size.
 */
int ntfs_setattr(struct dentry *dentry, struct iattr *attr)
{
        struct inode *vi;
        int err;
        unsigned int ia_valid = attr->ia_valid;

        vi = dentry->d_inode;

        err = inode_change_ok(vi, attr);
        if (err)
                return err;

        if ((ia_valid & ATTR_UID && attr->ia_uid != vi->i_uid) ||
                        (ia_valid & ATTR_GID && attr->ia_gid != vi->i_gid)) {
                err = DQUOT_TRANSFER(vi, attr) ? -EDQUOT : 0;
                if (err)
                        return err;
        }

        lock_kernel();

        if (ia_valid & ATTR_SIZE) {
                ntfs_error(vi->i_sb, "Changes in i_size are not supported "
                                "yet. Sorry.");
                // TODO: Implement...
                // err = vmtruncate(vi, attr->ia_size);
                err = -EOPNOTSUPP;
                if (err)
                        goto trunc_err;
        }

        if (ia_valid & ATTR_UID)
                vi->i_uid = attr->ia_uid;
        if (ia_valid & ATTR_GID)
                vi->i_gid = attr->ia_gid;
        if (ia_valid & ATTR_ATIME)
                vi->i_atime = attr->ia_atime;
        if (ia_valid & ATTR_MTIME)
                vi->i_mtime = attr->ia_mtime;
        if (ia_valid & ATTR_CTIME)
                vi->i_ctime = attr->ia_ctime;
        if (ia_valid & ATTR_MODE) {
                vi->i_mode = attr->ia_mode;
                if (!in_group_p(vi->i_gid) &&
                                !capable(CAP_FSETID))
                        vi->i_mode &= ~S_ISGID;
        }
        mark_inode_dirty(vi);

trunc_err:

        unlock_kernel();

        return err;
}

#endif