--- /dev/null
+/*
+ * linux/fs/ext4/balloc.c
+ *
+ * Copyright (C) 1992, 1993, 1994, 1995
+ * Remy Card (card@masi.ibp.fr)
+ * Laboratoire MASI - Institut Blaise Pascal
+ * Universite Pierre et Marie Curie (Paris VI)
+ *
+ * Enhanced block allocation by Stephen Tweedie (sct@redhat.com), 1993
+ * Big-endian to little-endian byte-swapping/bitmaps by
+ * David S. Miller (davem@caip.rutgers.edu), 1995
+ */
+
+#include <linux/time.h>
+#include <linux/capability.h>
+#include <linux/fs.h>
+#include <linux/jbd2.h>
+#include <linux/ext4_fs.h>
+#include <linux/ext4_jbd2.h>
+#include <linux/quotaops.h>
+#include <linux/buffer_head.h>
+#include <linux/vs_dlimit.h>
+#include <linux/vs_tag.h>
+
+/*
+ * balloc.c contains the blocks allocation and deallocation routines
+ */
+
+/*
+ * Calculate the block group number and offset, given a block number
+ */
+void ext4_get_group_no_and_offset(struct super_block *sb, ext4_fsblk_t blocknr,
+ unsigned long *blockgrpp, ext4_grpblk_t *offsetp)
+{
+ struct ext4_super_block *es = EXT4_SB(sb)->s_es;
+ ext4_grpblk_t offset;
+
+ blocknr = blocknr - le32_to_cpu(es->s_first_data_block);
+ offset = do_div(blocknr, EXT4_BLOCKS_PER_GROUP(sb));
+ if (offsetp)
+ *offsetp = offset;
+ if (blockgrpp)
+ *blockgrpp = blocknr;
+
+}
+
+/*
+ * The free blocks are managed by bitmaps. A file system contains several
+ * blocks groups. Each group contains 1 bitmap block for blocks, 1 bitmap
+ * block for inodes, N blocks for the inode table and data blocks.
+ *
+ * The file system contains group descriptors which are located after the
+ * super block. Each descriptor contains the number of the bitmap block and
+ * the free blocks count in the block. The descriptors are loaded in memory
+ * when a file system is mounted (see ext4_read_super).
+ */
+
+
+#define in_range(b, first, len) ((b) >= (first) && (b) <= (first) + (len) - 1)
+
+/**
+ * ext4_get_group_desc() -- load group descriptor from disk
+ * @sb: super block
+ * @block_group: given block group
+ * @bh: pointer to the buffer head to store the block
+ * group descriptor
+ */
+struct ext4_group_desc * ext4_get_group_desc(struct super_block * sb,
+ unsigned int block_group,
+ struct buffer_head ** bh)
+{
+ unsigned long group_desc;
+ unsigned long offset;
+ struct ext4_group_desc * desc;
+ struct ext4_sb_info *sbi = EXT4_SB(sb);
+
+ if (block_group >= sbi->s_groups_count) {
+ ext4_error (sb, "ext4_get_group_desc",
+ "block_group >= groups_count - "
+ "block_group = %d, groups_count = %lu",
+ block_group, sbi->s_groups_count);
+
+ return NULL;
+ }
+ smp_rmb();
+
+ group_desc = block_group >> EXT4_DESC_PER_BLOCK_BITS(sb);
+ offset = block_group & (EXT4_DESC_PER_BLOCK(sb) - 1);
+ if (!sbi->s_group_desc[group_desc]) {
+ ext4_error (sb, "ext4_get_group_desc",
+ "Group descriptor not loaded - "
+ "block_group = %d, group_desc = %lu, desc = %lu",
+ block_group, group_desc, offset);
+ return NULL;
+ }
+
+ desc = (struct ext4_group_desc *)(
+ (__u8 *)sbi->s_group_desc[group_desc]->b_data +
+ offset * EXT4_DESC_SIZE(sb));
+ if (bh)
+ *bh = sbi->s_group_desc[group_desc];
+ return desc;
+}
+
+/**
+ * read_block_bitmap()
+ * @sb: super block
+ * @block_group: given block group
+ *
+ * Read the bitmap for a given block_group, reading into the specified
+ * slot in the superblock's bitmap cache.
+ *
+ * Return buffer_head on success or NULL in case of failure.
+ */
+static struct buffer_head *
+read_block_bitmap(struct super_block *sb, unsigned int block_group)
+{
+ struct ext4_group_desc * desc;
+ struct buffer_head * bh = NULL;
+
+ desc = ext4_get_group_desc (sb, block_group, NULL);
+ if (!desc)
+ goto error_out;
+ bh = sb_bread(sb, ext4_block_bitmap(sb, desc));
+ if (!bh)
+ ext4_error (sb, "read_block_bitmap",
+ "Cannot read block bitmap - "
+ "block_group = %d, block_bitmap = %llu",
+ block_group,
+ ext4_block_bitmap(sb, desc));
+error_out:
+ return bh;
+}
+/*
+ * The reservation window structure operations
+ * --------------------------------------------
+ * Operations include:
+ * dump, find, add, remove, is_empty, find_next_reservable_window, etc.
+ *
+ * We use a red-black tree to represent per-filesystem reservation
+ * windows.
+ *
+ */
+
+/**
+ * __rsv_window_dump() -- Dump the filesystem block allocation reservation map
+ * @rb_root: root of per-filesystem reservation rb tree
+ * @verbose: verbose mode
+ * @fn: function which wishes to dump the reservation map
+ *
+ * If verbose is turned on, it will print the whole block reservation
+ * windows(start, end). Otherwise, it will only print out the "bad" windows,
+ * those windows that overlap with their immediate neighbors.
+ */
+#if 1
+static void __rsv_window_dump(struct rb_root *root, int verbose,
+ const char *fn)
+{
+ struct rb_node *n;
+ struct ext4_reserve_window_node *rsv, *prev;
+ int bad;
+
+restart:
+ n = rb_first(root);
+ bad = 0;
+ prev = NULL;
+
+ printk("Block Allocation Reservation Windows Map (%s):\n", fn);
+ while (n) {
+ rsv = rb_entry(n, struct ext4_reserve_window_node, rsv_node);
+ if (verbose)
+ printk("reservation window 0x%p "
+ "start: %llu, end: %llu\n",
+ rsv, rsv->rsv_start, rsv->rsv_end);
+ if (rsv->rsv_start && rsv->rsv_start >= rsv->rsv_end) {
+ printk("Bad reservation %p (start >= end)\n",
+ rsv);
+ bad = 1;
+ }
+ if (prev && prev->rsv_end >= rsv->rsv_start) {
+ printk("Bad reservation %p (prev->end >= start)\n",
+ rsv);
+ bad = 1;
+ }
+ if (bad) {
+ if (!verbose) {
+ printk("Restarting reservation walk in verbose mode\n");
+ verbose = 1;
+ goto restart;
+ }
+ }
+ n = rb_next(n);
+ prev = rsv;
+ }
+ printk("Window map complete.\n");
+ if (bad)
+ BUG();
+}
+#define rsv_window_dump(root, verbose) \
+ __rsv_window_dump((root), (verbose), __FUNCTION__)
+#else
+#define rsv_window_dump(root, verbose) do {} while (0)
+#endif
+
+/**
+ * goal_in_my_reservation()
+ * @rsv: inode's reservation window
+ * @grp_goal: given goal block relative to the allocation block group
+ * @group: the current allocation block group
+ * @sb: filesystem super block
+ *
+ * Test if the given goal block (group relative) is within the file's
+ * own block reservation window range.
+ *
+ * If the reservation window is outside the goal allocation group, return 0;
+ * grp_goal (given goal block) could be -1, which means no specific
+ * goal block. In this case, always return 1.
+ * If the goal block is within the reservation window, return 1;
+ * otherwise, return 0;
+ */
+static int
+goal_in_my_reservation(struct ext4_reserve_window *rsv, ext4_grpblk_t grp_goal,
+ unsigned int group, struct super_block * sb)
+{
+ ext4_fsblk_t group_first_block, group_last_block;
+
+ group_first_block = ext4_group_first_block_no(sb, group);
+ group_last_block = group_first_block + (EXT4_BLOCKS_PER_GROUP(sb) - 1);
+
+ if ((rsv->_rsv_start > group_last_block) ||
+ (rsv->_rsv_end < group_first_block))
+ return 0;
+ if ((grp_goal >= 0) && ((grp_goal + group_first_block < rsv->_rsv_start)
+ || (grp_goal + group_first_block > rsv->_rsv_end)))
+ return 0;
+ return 1;
+}
+
+/**
+ * search_reserve_window()
+ * @rb_root: root of reservation tree
+ * @goal: target allocation block
+ *
+ * Find the reserved window which includes the goal, or the previous one
+ * if the goal is not in any window.
+ * Returns NULL if there are no windows or if all windows start after the goal.
+ */
+static struct ext4_reserve_window_node *
+search_reserve_window(struct rb_root *root, ext4_fsblk_t goal)
+{
+ struct rb_node *n = root->rb_node;
+ struct ext4_reserve_window_node *rsv;
+
+ if (!n)
+ return NULL;
+
+ do {
+ rsv = rb_entry(n, struct ext4_reserve_window_node, rsv_node);
+
+ if (goal < rsv->rsv_start)
+ n = n->rb_left;
+ else if (goal > rsv->rsv_end)
+ n = n->rb_right;
+ else
+ return rsv;
+ } while (n);
+ /*
+ * We've fallen off the end of the tree: the goal wasn't inside
+ * any particular node. OK, the previous node must be to one
+ * side of the interval containing the goal. If it's the RHS,
+ * we need to back up one.
+ */
+ if (rsv->rsv_start > goal) {
+ n = rb_prev(&rsv->rsv_node);
+ rsv = rb_entry(n, struct ext4_reserve_window_node, rsv_node);
+ }
+ return rsv;
+}
+
+/**
+ * ext4_rsv_window_add() -- Insert a window to the block reservation rb tree.
+ * @sb: super block
+ * @rsv: reservation window to add
+ *
+ * Must be called with rsv_lock hold.
+ */
+void ext4_rsv_window_add(struct super_block *sb,
+ struct ext4_reserve_window_node *rsv)
+{
+ struct rb_root *root = &EXT4_SB(sb)->s_rsv_window_root;
+ struct rb_node *node = &rsv->rsv_node;
+ ext4_fsblk_t start = rsv->rsv_start;
+
+ struct rb_node ** p = &root->rb_node;
+ struct rb_node * parent = NULL;
+ struct ext4_reserve_window_node *this;
+
+ while (*p)
+ {
+ parent = *p;
+ this = rb_entry(parent, struct ext4_reserve_window_node, rsv_node);
+
+ if (start < this->rsv_start)
+ p = &(*p)->rb_left;
+ else if (start > this->rsv_end)
+ p = &(*p)->rb_right;
+ else {
+ rsv_window_dump(root, 1);
+ BUG();
+ }
+ }
+
+ rb_link_node(node, parent, p);
+ rb_insert_color(node, root);
+}
+
+/**
+ * ext4_rsv_window_remove() -- unlink a window from the reservation rb tree
+ * @sb: super block
+ * @rsv: reservation window to remove
+ *
+ * Mark the block reservation window as not allocated, and unlink it
+ * from the filesystem reservation window rb tree. Must be called with
+ * rsv_lock hold.
+ */
+static void rsv_window_remove(struct super_block *sb,
+ struct ext4_reserve_window_node *rsv)
+{
+ rsv->rsv_start = EXT4_RESERVE_WINDOW_NOT_ALLOCATED;
+ rsv->rsv_end = EXT4_RESERVE_WINDOW_NOT_ALLOCATED;
+ rsv->rsv_alloc_hit = 0;
+ rb_erase(&rsv->rsv_node, &EXT4_SB(sb)->s_rsv_window_root);
+}
+
+/*
+ * rsv_is_empty() -- Check if the reservation window is allocated.
+ * @rsv: given reservation window to check
+ *
+ * returns 1 if the end block is EXT4_RESERVE_WINDOW_NOT_ALLOCATED.
+ */
+static inline int rsv_is_empty(struct ext4_reserve_window *rsv)
+{
+ /* a valid reservation end block could not be 0 */
+ return rsv->_rsv_end == EXT4_RESERVE_WINDOW_NOT_ALLOCATED;
+}
+
+/**
+ * ext4_init_block_alloc_info()
+ * @inode: file inode structure
+ *
+ * Allocate and initialize the reservation window structure, and
+ * link the window to the ext4 inode structure at last
+ *
+ * The reservation window structure is only dynamically allocated
+ * and linked to ext4 inode the first time the open file
+ * needs a new block. So, before every ext4_new_block(s) call, for
+ * regular files, we should check whether the reservation window
+ * structure exists or not. In the latter case, this function is called.
+ * Fail to do so will result in block reservation being turned off for that
+ * open file.
+ *
+ * This function is called from ext4_get_blocks_handle(), also called
+ * when setting the reservation window size through ioctl before the file
+ * is open for write (needs block allocation).
+ *
+ * Needs truncate_mutex protection prior to call this function.
+ */
+void ext4_init_block_alloc_info(struct inode *inode)
+{
+ struct ext4_inode_info *ei = EXT4_I(inode);
+ struct ext4_block_alloc_info *block_i = ei->i_block_alloc_info;
+ struct super_block *sb = inode->i_sb;
+
+ block_i = kmalloc(sizeof(*block_i), GFP_NOFS);
+ if (block_i) {
+ struct ext4_reserve_window_node *rsv = &block_i->rsv_window_node;
+
+ rsv->rsv_start = EXT4_RESERVE_WINDOW_NOT_ALLOCATED;
+ rsv->rsv_end = EXT4_RESERVE_WINDOW_NOT_ALLOCATED;
+
+ /*
+ * if filesystem is mounted with NORESERVATION, the goal
+ * reservation window size is set to zero to indicate
+ * block reservation is off
+ */
+ if (!test_opt(sb, RESERVATION))
+ rsv->rsv_goal_size = 0;
+ else
+ rsv->rsv_goal_size = EXT4_DEFAULT_RESERVE_BLOCKS;
+ rsv->rsv_alloc_hit = 0;
+ block_i->last_alloc_logical_block = 0;
+ block_i->last_alloc_physical_block = 0;
+ }
+ ei->i_block_alloc_info = block_i;
+}
+
+/**
+ * ext4_discard_reservation()
+ * @inode: inode
+ *
+ * Discard(free) block reservation window on last file close, or truncate
+ * or at last iput().
+ *
+ * It is being called in three cases:
+ * ext4_release_file(): last writer close the file
+ * ext4_clear_inode(): last iput(), when nobody link to this file.
+ * ext4_truncate(): when the block indirect map is about to change.
+ *
+ */
+void ext4_discard_reservation(struct inode *inode)
+{
+ struct ext4_inode_info *ei = EXT4_I(inode);
+ struct ext4_block_alloc_info *block_i = ei->i_block_alloc_info;
+ struct ext4_reserve_window_node *rsv;
+ spinlock_t *rsv_lock = &EXT4_SB(inode->i_sb)->s_rsv_window_lock;
+
+ if (!block_i)
+ return;
+
+ rsv = &block_i->rsv_window_node;
+ if (!rsv_is_empty(&rsv->rsv_window)) {
+ spin_lock(rsv_lock);
+ if (!rsv_is_empty(&rsv->rsv_window))
+ rsv_window_remove(inode->i_sb, rsv);
+ spin_unlock(rsv_lock);
+ }
+}
+
+/**
+ * ext4_free_blocks_sb() -- Free given blocks and update quota
+ * @handle: handle to this transaction
+ * @sb: super block
+ * @block: start physcial block to free
+ * @count: number of blocks to free
+ * @pdquot_freed_blocks: pointer to quota
+ */
+void ext4_free_blocks_sb(handle_t *handle, struct super_block *sb,
+ ext4_fsblk_t block, unsigned long count,
+ unsigned long *pdquot_freed_blocks)
+{
+ struct buffer_head *bitmap_bh = NULL;
+ struct buffer_head *gd_bh;
+ unsigned long block_group;
+ ext4_grpblk_t bit;
+ unsigned long i;
+ unsigned long overflow;
+ struct ext4_group_desc * desc;
+ struct ext4_super_block * es;
+ struct ext4_sb_info *sbi;
+ int err = 0, ret;
+ ext4_grpblk_t group_freed;
+
+ *pdquot_freed_blocks = 0;
+ sbi = EXT4_SB(sb);
+ es = sbi->s_es;
+ if (block < le32_to_cpu(es->s_first_data_block) ||
+ block + count < block ||
+ block + count > ext4_blocks_count(es)) {
+ ext4_error (sb, "ext4_free_blocks",
+ "Freeing blocks not in datazone - "
+ "block = %llu, count = %lu", block, count);
+ goto error_return;
+ }
+
+ ext4_debug ("freeing block(s) %llu-%llu\n", block, block + count - 1);
+
+do_more:
+ overflow = 0;
+ ext4_get_group_no_and_offset(sb, block, &block_group, &bit);
+ /*
+ * Check to see if we are freeing blocks across a group
+ * boundary.
+ */
+ if (bit + count > EXT4_BLOCKS_PER_GROUP(sb)) {
+ overflow = bit + count - EXT4_BLOCKS_PER_GROUP(sb);
+ count -= overflow;
+ }
+ brelse(bitmap_bh);
+ bitmap_bh = read_block_bitmap(sb, block_group);
+ if (!bitmap_bh)
+ goto error_return;
+ desc = ext4_get_group_desc (sb, block_group, &gd_bh);
+ if (!desc)
+ goto error_return;
+
+ if (in_range(ext4_block_bitmap(sb, desc), block, count) ||
+ in_range(ext4_inode_bitmap(sb, desc), block, count) ||
+ in_range(block, ext4_inode_table(sb, desc), sbi->s_itb_per_group) ||
+ in_range(block + count - 1, ext4_inode_table(sb, desc),
+ sbi->s_itb_per_group))
+ ext4_error (sb, "ext4_free_blocks",
+ "Freeing blocks in system zones - "
+ "Block = %llu, count = %lu",
+ block, count);
+
+ /*
+ * We are about to start releasing blocks in the bitmap,
+ * so we need undo access.
+ */
+ /* @@@ check errors */
+ BUFFER_TRACE(bitmap_bh, "getting undo access");
+ err = ext4_journal_get_undo_access(handle, bitmap_bh);
+ if (err)
+ goto error_return;
+
+ /*
+ * We are about to modify some metadata. Call the journal APIs
+ * to unshare ->b_data if a currently-committing transaction is
+ * using it
+ */
+ BUFFER_TRACE(gd_bh, "get_write_access");
+ err = ext4_journal_get_write_access(handle, gd_bh);
+ if (err)
+ goto error_return;
+
+ jbd_lock_bh_state(bitmap_bh);
+
+ for (i = 0, group_freed = 0; i < count; i++) {
+ /*
+ * An HJ special. This is expensive...
+ */
+#ifdef CONFIG_JBD_DEBUG
+ jbd_unlock_bh_state(bitmap_bh);
+ {
+ struct buffer_head *debug_bh;
+ debug_bh = sb_find_get_block(sb, block + i);
+ if (debug_bh) {
+ BUFFER_TRACE(debug_bh, "Deleted!");
+ if (!bh2jh(bitmap_bh)->b_committed_data)
+ BUFFER_TRACE(debug_bh,
+ "No commited data in bitmap");
+ BUFFER_TRACE2(debug_bh, bitmap_bh, "bitmap");
+ __brelse(debug_bh);
+ }
+ }
+ jbd_lock_bh_state(bitmap_bh);
+#endif
+ if (need_resched()) {
+ jbd_unlock_bh_state(bitmap_bh);
+ cond_resched();
+ jbd_lock_bh_state(bitmap_bh);
+ }
+ /* @@@ This prevents newly-allocated data from being
+ * freed and then reallocated within the same
+ * transaction.
+ *
+ * Ideally we would want to allow that to happen, but to
+ * do so requires making jbd2_journal_forget() capable of
+ * revoking the queued write of a data block, which
+ * implies blocking on the journal lock. *forget()
+ * cannot block due to truncate races.
+ *
+ * Eventually we can fix this by making jbd2_journal_forget()
+ * return a status indicating whether or not it was able
+ * to revoke the buffer. On successful revoke, it is
+ * safe not to set the allocation bit in the committed
+ * bitmap, because we know that there is no outstanding
+ * activity on the buffer any more and so it is safe to
+ * reallocate it.
+ */
+ BUFFER_TRACE(bitmap_bh, "set in b_committed_data");
+ J_ASSERT_BH(bitmap_bh,
+ bh2jh(bitmap_bh)->b_committed_data != NULL);
+ ext4_set_bit_atomic(sb_bgl_lock(sbi, block_group), bit + i,
+ bh2jh(bitmap_bh)->b_committed_data);
+
+ /*
+ * We clear the bit in the bitmap after setting the committed
+ * data bit, because this is the reverse order to that which
+ * the allocator uses.
+ */
+ BUFFER_TRACE(bitmap_bh, "clear bit");
+ if (!ext4_clear_bit_atomic(sb_bgl_lock(sbi, block_group),
+ bit + i, bitmap_bh->b_data)) {
+ jbd_unlock_bh_state(bitmap_bh);
+ ext4_error(sb, __FUNCTION__,
+ "bit already cleared for block %llu",
+ (ext4_fsblk_t)(block + i));
+ jbd_lock_bh_state(bitmap_bh);
+ BUFFER_TRACE(bitmap_bh, "bit already cleared");
+ } else {
+ group_freed++;
+ }
+ }
+ jbd_unlock_bh_state(bitmap_bh);
+
+ spin_lock(sb_bgl_lock(sbi, block_group));
+ desc->bg_free_blocks_count =
+ cpu_to_le16(le16_to_cpu(desc->bg_free_blocks_count) +
+ group_freed);
+ spin_unlock(sb_bgl_lock(sbi, block_group));
+ percpu_counter_mod(&sbi->s_freeblocks_counter, count);
+
+ /* We dirtied the bitmap block */
+ BUFFER_TRACE(bitmap_bh, "dirtied bitmap block");
+ err = ext4_journal_dirty_metadata(handle, bitmap_bh);
+
+ /* And the group descriptor block */
+ BUFFER_TRACE(gd_bh, "dirtied group descriptor block");
+ ret = ext4_journal_dirty_metadata(handle, gd_bh);
+ if (!err) err = ret;
+ *pdquot_freed_blocks += group_freed;
+
+ if (overflow && !err) {
+ block += count;
+ count = overflow;
+ goto do_more;
+ }
+ sb->s_dirt = 1;
+error_return:
+ brelse(bitmap_bh);
+ ext4_std_error(sb, err);
+ return;
+}
+
+/**
+ * ext4_free_blocks() -- Free given blocks and update quota
+ * @handle: handle for this transaction
+ * @inode: inode
+ * @block: start physical block to free
+ * @count: number of blocks to count
+ */
+void ext4_free_blocks(handle_t *handle, struct inode *inode,
+ ext4_fsblk_t block, unsigned long count)
+{
+ struct super_block * sb;
+ unsigned long dquot_freed_blocks;
+
+ sb = inode->i_sb;
+ if (!sb) {
+ printk ("ext4_free_blocks: nonexistent device");
+ return;
+ }
+ ext4_free_blocks_sb(handle, sb, block, count, &dquot_freed_blocks);
+ if (dquot_freed_blocks) {
+ DLIMIT_FREE_BLOCK(inode, dquot_freed_blocks);
+ DQUOT_FREE_BLOCK(inode, dquot_freed_blocks);
+ }
+ return;
+}
+
+/**
+ * ext4_test_allocatable()
+ * @nr: given allocation block group
+ * @bh: bufferhead contains the bitmap of the given block group
+ *
+ * For ext4 allocations, we must not reuse any blocks which are
+ * allocated in the bitmap buffer's "last committed data" copy. This
+ * prevents deletes from freeing up the page for reuse until we have
+ * committed the delete transaction.
+ *
+ * If we didn't do this, then deleting something and reallocating it as
+ * data would allow the old block to be overwritten before the
+ * transaction committed (because we force data to disk before commit).
+ * This would lead to corruption if we crashed between overwriting the
+ * data and committing the delete.
+ *
+ * @@@ We may want to make this allocation behaviour conditional on
+ * data-writes at some point, and disable it for metadata allocations or
+ * sync-data inodes.
+ */
+static int ext4_test_allocatable(ext4_grpblk_t nr, struct buffer_head *bh)
+{
+ int ret;
+ struct journal_head *jh = bh2jh(bh);
+
+ if (ext4_test_bit(nr, bh->b_data))
+ return 0;
+
+ jbd_lock_bh_state(bh);
+ if (!jh->b_committed_data)
+ ret = 1;
+ else
+ ret = !ext4_test_bit(nr, jh->b_committed_data);
+ jbd_unlock_bh_state(bh);
+ return ret;
+}
+
+/**
+ * bitmap_search_next_usable_block()
+ * @start: the starting block (group relative) of the search
+ * @bh: bufferhead contains the block group bitmap
+ * @maxblocks: the ending block (group relative) of the reservation
+ *
+ * The bitmap search --- search forward alternately through the actual
+ * bitmap on disk and the last-committed copy in journal, until we find a
+ * bit free in both bitmaps.
+ */
+static ext4_grpblk_t
+bitmap_search_next_usable_block(ext4_grpblk_t start, struct buffer_head *bh,
+ ext4_grpblk_t maxblocks)
+{
+ ext4_grpblk_t next;
+ struct journal_head *jh = bh2jh(bh);
+
+ while (start < maxblocks) {
+ next = ext4_find_next_zero_bit(bh->b_data, maxblocks, start);
+ if (next >= maxblocks)
+ return -1;
+ if (ext4_test_allocatable(next, bh))
+ return next;
+ jbd_lock_bh_state(bh);
+ if (jh->b_committed_data)
+ start = ext4_find_next_zero_bit(jh->b_committed_data,
+ maxblocks, next);
+ jbd_unlock_bh_state(bh);
+ }
+ return -1;
+}
+
+/**
+ * find_next_usable_block()
+ * @start: the starting block (group relative) to find next
+ * allocatable block in bitmap.
+ * @bh: bufferhead contains the block group bitmap
+ * @maxblocks: the ending block (group relative) for the search
+ *
+ * Find an allocatable block in a bitmap. We honor both the bitmap and
+ * its last-committed copy (if that exists), and perform the "most
+ * appropriate allocation" algorithm of looking for a free block near
+ * the initial goal; then for a free byte somewhere in the bitmap; then
+ * for any free bit in the bitmap.
+ */
+static ext4_grpblk_t
+find_next_usable_block(ext4_grpblk_t start, struct buffer_head *bh,
+ ext4_grpblk_t maxblocks)
+{
+ ext4_grpblk_t here, next;
+ char *p, *r;
+
+ if (start > 0) {
+ /*
+ * The goal was occupied; search forward for a free
+ * block within the next XX blocks.
+ *
+ * end_goal is more or less random, but it has to be
+ * less than EXT4_BLOCKS_PER_GROUP. Aligning up to the
+ * next 64-bit boundary is simple..
+ */
+ ext4_grpblk_t end_goal = (start + 63) & ~63;
+ if (end_goal > maxblocks)
+ end_goal = maxblocks;
+ here = ext4_find_next_zero_bit(bh->b_data, end_goal, start);
+ if (here < end_goal && ext4_test_allocatable(here, bh))
+ return here;
+ ext4_debug("Bit not found near goal\n");
+ }
+
+ here = start;
+ if (here < 0)
+ here = 0;
+
+ p = ((char *)bh->b_data) + (here >> 3);
+ r = memscan(p, 0, ((maxblocks + 7) >> 3) - (here >> 3));
+ next = (r - ((char *)bh->b_data)) << 3;
+
+ if (next < maxblocks && next >= start && ext4_test_allocatable(next, bh))
+ return next;
+
+ /*
+ * The bitmap search --- search forward alternately through the actual
+ * bitmap and the last-committed copy until we find a bit free in
+ * both
+ */
+ here = bitmap_search_next_usable_block(here, bh, maxblocks);
+ return here;
+}
+
+/**
+ * claim_block()
+ * @block: the free block (group relative) to allocate
+ * @bh: the bufferhead containts the block group bitmap
+ *
+ * We think we can allocate this block in this bitmap. Try to set the bit.
+ * If that succeeds then check that nobody has allocated and then freed the
+ * block since we saw that is was not marked in b_committed_data. If it _was_
+ * allocated and freed then clear the bit in the bitmap again and return
+ * zero (failure).
+ */
+static inline int
+claim_block(spinlock_t *lock, ext4_grpblk_t block, struct buffer_head *bh)
+{
+ struct journal_head *jh = bh2jh(bh);
+ int ret;
+
+ if (ext4_set_bit_atomic(lock, block, bh->b_data))
+ return 0;
+ jbd_lock_bh_state(bh);
+ if (jh->b_committed_data && ext4_test_bit(block,jh->b_committed_data)) {
+ ext4_clear_bit_atomic(lock, block, bh->b_data);
+ ret = 0;
+ } else {
+ ret = 1;
+ }
+ jbd_unlock_bh_state(bh);
+ return ret;
+}
+
+/**
+ * ext4_try_to_allocate()
+ * @sb: superblock
+ * @handle: handle to this transaction
+ * @group: given allocation block group
+ * @bitmap_bh: bufferhead holds the block bitmap
+ * @grp_goal: given target block within the group
+ * @count: target number of blocks to allocate
+ * @my_rsv: reservation window
+ *
+ * Attempt to allocate blocks within a give range. Set the range of allocation
+ * first, then find the first free bit(s) from the bitmap (within the range),
+ * and at last, allocate the blocks by claiming the found free bit as allocated.
+ *
+ * To set the range of this allocation:
+ * if there is a reservation window, only try to allocate block(s) from the
+ * file's own reservation window;
+ * Otherwise, the allocation range starts from the give goal block, ends at
+ * the block group's last block.
+ *
+ * If we failed to allocate the desired block then we may end up crossing to a
+ * new bitmap. In that case we must release write access to the old one via
+ * ext4_journal_release_buffer(), else we'll run out of credits.
+ */
+static ext4_grpblk_t
+ext4_try_to_allocate(struct super_block *sb, handle_t *handle, int group,
+ struct buffer_head *bitmap_bh, ext4_grpblk_t grp_goal,
+ unsigned long *count, struct ext4_reserve_window *my_rsv)
+{
+ ext4_fsblk_t group_first_block;
+ ext4_grpblk_t start, end;
+ unsigned long num = 0;
+
+ /* we do allocation within the reservation window if we have a window */
+ if (my_rsv) {
+ group_first_block = ext4_group_first_block_no(sb, group);
+ if (my_rsv->_rsv_start >= group_first_block)
+ start = my_rsv->_rsv_start - group_first_block;
+ else
+ /* reservation window cross group boundary */
+ start = 0;
+ end = my_rsv->_rsv_end - group_first_block + 1;
+ if (end > EXT4_BLOCKS_PER_GROUP(sb))
+ /* reservation window crosses group boundary */
+ end = EXT4_BLOCKS_PER_GROUP(sb);
+ if ((start <= grp_goal) && (grp_goal < end))
+ start = grp_goal;
+ else
+ grp_goal = -1;
+ } else {
+ if (grp_goal > 0)
+ start = grp_goal;
+ else
+ start = 0;
+ end = EXT4_BLOCKS_PER_GROUP(sb);
+ }
+
+ BUG_ON(start > EXT4_BLOCKS_PER_GROUP(sb));
+
+repeat:
+ if (grp_goal < 0 || !ext4_test_allocatable(grp_goal, bitmap_bh)) {
+ grp_goal = find_next_usable_block(start, bitmap_bh, end);
+ if (grp_goal < 0)
+ goto fail_access;
+ if (!my_rsv) {
+ int i;
+
+ for (i = 0; i < 7 && grp_goal > start &&
+ ext4_test_allocatable(grp_goal - 1,
+ bitmap_bh);
+ i++, grp_goal--)
+ ;
+ }
+ }
+ start = grp_goal;
+
+ if (!claim_block(sb_bgl_lock(EXT4_SB(sb), group),
+ grp_goal, bitmap_bh)) {
+ /*
+ * The block was allocated by another thread, or it was
+ * allocated and then freed by another thread
+ */
+ start++;
+ grp_goal++;
+ if (start >= end)
+ goto fail_access;
+ goto repeat;
+ }
+ num++;
+ grp_goal++;
+ while (num < *count && grp_goal < end
+ && ext4_test_allocatable(grp_goal, bitmap_bh)
+ && claim_block(sb_bgl_lock(EXT4_SB(sb), group),
+ grp_goal, bitmap_bh)) {
+ num++;
+ grp_goal++;
+ }
+ *count = num;
+ return grp_goal - num;
+fail_access:
+ *count = num;
+ return -1;
+}
+
+/**
+ * find_next_reservable_window():
+ * find a reservable space within the given range.
+ * It does not allocate the reservation window for now:
+ * alloc_new_reservation() will do the work later.
+ *
+ * @search_head: the head of the searching list;
+ * This is not necessarily the list head of the whole filesystem
+ *
+ * We have both head and start_block to assist the search
+ * for the reservable space. The list starts from head,
+ * but we will shift to the place where start_block is,
+ * then start from there, when looking for a reservable space.
+ *
+ * @size: the target new reservation window size
+ *
+ * @group_first_block: the first block we consider to start
+ * the real search from
+ *
+ * @last_block:
+ * the maximum block number that our goal reservable space
+ * could start from. This is normally the last block in this
+ * group. The search will end when we found the start of next
+ * possible reservable space is out of this boundary.
+ * This could handle the cross boundary reservation window
+ * request.
+ *
+ * basically we search from the given range, rather than the whole
+ * reservation double linked list, (start_block, last_block)
+ * to find a free region that is of my size and has not
+ * been reserved.
+ *
+ */
+static int find_next_reservable_window(
+ struct ext4_reserve_window_node *search_head,
+ struct ext4_reserve_window_node *my_rsv,
+ struct super_block * sb,
+ ext4_fsblk_t start_block,
+ ext4_fsblk_t last_block)
+{
+ struct rb_node *next;
+ struct ext4_reserve_window_node *rsv, *prev;
+ ext4_fsblk_t cur;
+ int size = my_rsv->rsv_goal_size;
+
+ /* TODO: make the start of the reservation window byte-aligned */
+ /* cur = *start_block & ~7;*/
+ cur = start_block;
+ rsv = search_head;
+ if (!rsv)
+ return -1;
+
+ while (1) {
+ if (cur <= rsv->rsv_end)
+ cur = rsv->rsv_end + 1;
+
+ /* TODO?
+ * in the case we could not find a reservable space
+ * that is what is expected, during the re-search, we could
+ * remember what's the largest reservable space we could have
+ * and return that one.
+ *
+ * For now it will fail if we could not find the reservable
+ * space with expected-size (or more)...
+ */
+ if (cur > last_block)
+ return -1; /* fail */
+
+ prev = rsv;
+ next = rb_next(&rsv->rsv_node);
+ rsv = rb_entry(next,struct ext4_reserve_window_node,rsv_node);
+
+ /*
+ * Reached the last reservation, we can just append to the
+ * previous one.
+ */
+ if (!next)
+ break;
+
+ if (cur + size <= rsv->rsv_start) {
+ /*
+ * Found a reserveable space big enough. We could
+ * have a reservation across the group boundary here
+ */
+ break;
+ }
+ }
+ /*
+ * we come here either :
+ * when we reach the end of the whole list,
+ * and there is empty reservable space after last entry in the list.
+ * append it to the end of the list.
+ *
+ * or we found one reservable space in the middle of the list,
+ * return the reservation window that we could append to.
+ * succeed.
+ */
+
+ if ((prev != my_rsv) && (!rsv_is_empty(&my_rsv->rsv_window)))
+ rsv_window_remove(sb, my_rsv);
+
+ /*
+ * Let's book the whole avaliable window for now. We will check the
+ * disk bitmap later and then, if there are free blocks then we adjust
+ * the window size if it's larger than requested.
+ * Otherwise, we will remove this node from the tree next time
+ * call find_next_reservable_window.
+ */
+ my_rsv->rsv_start = cur;
+ my_rsv->rsv_end = cur + size - 1;
+ my_rsv->rsv_alloc_hit = 0;
+
+ if (prev != my_rsv)
+ ext4_rsv_window_add(sb, my_rsv);
+
+ return 0;
+}
+
+/**
+ * alloc_new_reservation()--allocate a new reservation window
+ *
+ * To make a new reservation, we search part of the filesystem
+ * reservation list (the list that inside the group). We try to
+ * allocate a new reservation window near the allocation goal,
+ * or the beginning of the group, if there is no goal.
+ *
+ * We first find a reservable space after the goal, then from
+ * there, we check the bitmap for the first free block after
+ * it. If there is no free block until the end of group, then the
+ * whole group is full, we failed. Otherwise, check if the free
+ * block is inside the expected reservable space, if so, we
+ * succeed.
+ * If the first free block is outside the reservable space, then
+ * start from the first free block, we search for next available
+ * space, and go on.
+ *
+ * on succeed, a new reservation will be found and inserted into the list
+ * It contains at least one free block, and it does not overlap with other
+ * reservation windows.
+ *
+ * failed: we failed to find a reservation window in this group
+ *
+ * @rsv: the reservation
+ *
+ * @grp_goal: The goal (group-relative). It is where the search for a
+ * free reservable space should start from.
+ * if we have a grp_goal(grp_goal >0 ), then start from there,
+ * no grp_goal(grp_goal = -1), we start from the first block
+ * of the group.
+ *
+ * @sb: the super block
+ * @group: the group we are trying to allocate in
+ * @bitmap_bh: the block group block bitmap
+ *
+ */
+static int alloc_new_reservation(struct ext4_reserve_window_node *my_rsv,
+ ext4_grpblk_t grp_goal, struct super_block *sb,
+ unsigned int group, struct buffer_head *bitmap_bh)
+{
+ struct ext4_reserve_window_node *search_head;
+ ext4_fsblk_t group_first_block, group_end_block, start_block;
+ ext4_grpblk_t first_free_block;
+ struct rb_root *fs_rsv_root = &EXT4_SB(sb)->s_rsv_window_root;
+ unsigned long size;
+ int ret;
+ spinlock_t *rsv_lock = &EXT4_SB(sb)->s_rsv_window_lock;
+
+ group_first_block = ext4_group_first_block_no(sb, group);
+ group_end_block = group_first_block + (EXT4_BLOCKS_PER_GROUP(sb) - 1);
+
+ if (grp_goal < 0)
+ start_block = group_first_block;
+ else
+ start_block = grp_goal + group_first_block;
+
+ size = my_rsv->rsv_goal_size;
+
+ if (!rsv_is_empty(&my_rsv->rsv_window)) {
+ /*
+ * if the old reservation is cross group boundary
+ * and if the goal is inside the old reservation window,
+ * we will come here when we just failed to allocate from
+ * the first part of the window. We still have another part
+ * that belongs to the next group. In this case, there is no
+ * point to discard our window and try to allocate a new one
+ * in this group(which will fail). we should
+ * keep the reservation window, just simply move on.
+ *
+ * Maybe we could shift the start block of the reservation
+ * window to the first block of next group.
+ */
+
+ if ((my_rsv->rsv_start <= group_end_block) &&
+ (my_rsv->rsv_end > group_end_block) &&
+ (start_block >= my_rsv->rsv_start))
+ return -1;
+
+ if ((my_rsv->rsv_alloc_hit >
+ (my_rsv->rsv_end - my_rsv->rsv_start + 1) / 2)) {
+ /*
+ * if the previously allocation hit ratio is
+ * greater than 1/2, then we double the size of
+ * the reservation window the next time,
+ * otherwise we keep the same size window
+ */
+ size = size * 2;
+ if (size > EXT4_MAX_RESERVE_BLOCKS)
+ size = EXT4_MAX_RESERVE_BLOCKS;
+ my_rsv->rsv_goal_size= size;
+ }
+ }
+
+ spin_lock(rsv_lock);
+ /*
+ * shift the search start to the window near the goal block
+ */
+ search_head = search_reserve_window(fs_rsv_root, start_block);
+
+ /*
+ * find_next_reservable_window() simply finds a reservable window
+ * inside the given range(start_block, group_end_block).
+ *
+ * To make sure the reservation window has a free bit inside it, we
+ * need to check the bitmap after we found a reservable window.
+ */
+retry:
+ ret = find_next_reservable_window(search_head, my_rsv, sb,
+ start_block, group_end_block);
+
+ if (ret == -1) {
+ if (!rsv_is_empty(&my_rsv->rsv_window))
+ rsv_window_remove(sb, my_rsv);
+ spin_unlock(rsv_lock);
+ return -1;
+ }
+
+ /*
+ * On success, find_next_reservable_window() returns the
+ * reservation window where there is a reservable space after it.
+ * Before we reserve this reservable space, we need
+ * to make sure there is at least a free block inside this region.
+ *
+ * searching the first free bit on the block bitmap and copy of
+ * last committed bitmap alternatively, until we found a allocatable
+ * block. Search start from the start block of the reservable space
+ * we just found.
+ */
+ spin_unlock(rsv_lock);
+ first_free_block = bitmap_search_next_usable_block(
+ my_rsv->rsv_start - group_first_block,
+ bitmap_bh, group_end_block - group_first_block + 1);
+
+ if (first_free_block < 0) {
+ /*
+ * no free block left on the bitmap, no point
+ * to reserve the space. return failed.
+ */
+ spin_lock(rsv_lock);
+ if (!rsv_is_empty(&my_rsv->rsv_window))
+ rsv_window_remove(sb, my_rsv);
+ spin_unlock(rsv_lock);
+ return -1; /* failed */
+ }
+
+ start_block = first_free_block + group_first_block;
+ /*
+ * check if the first free block is within the
+ * free space we just reserved
+ */
+ if (start_block >= my_rsv->rsv_start && start_block <= my_rsv->rsv_end)
+ return 0; /* success */
+ /*
+ * if the first free bit we found is out of the reservable space
+ * continue search for next reservable space,
+ * start from where the free block is,
+ * we also shift the list head to where we stopped last time
+ */
+ search_head = my_rsv;
+ spin_lock(rsv_lock);
+ goto retry;
+}
+
+/**
+ * try_to_extend_reservation()
+ * @my_rsv: given reservation window
+ * @sb: super block
+ * @size: the delta to extend
+ *
+ * Attempt to expand the reservation window large enough to have
+ * required number of free blocks
+ *
+ * Since ext4_try_to_allocate() will always allocate blocks within
+ * the reservation window range, if the window size is too small,
+ * multiple blocks allocation has to stop at the end of the reservation
+ * window. To make this more efficient, given the total number of
+ * blocks needed and the current size of the window, we try to
+ * expand the reservation window size if necessary on a best-effort
+ * basis before ext4_new_blocks() tries to allocate blocks,
+ */
+static void try_to_extend_reservation(struct ext4_reserve_window_node *my_rsv,
+ struct super_block *sb, int size)
+{
+ struct ext4_reserve_window_node *next_rsv;
+ struct rb_node *next;
+ spinlock_t *rsv_lock = &EXT4_SB(sb)->s_rsv_window_lock;
+
+ if (!spin_trylock(rsv_lock))
+ return;
+
+ next = rb_next(&my_rsv->rsv_node);
+
+ if (!next)
+ my_rsv->rsv_end += size;
+ else {
+ next_rsv = rb_entry(next, struct ext4_reserve_window_node, rsv_node);
+
+ if ((next_rsv->rsv_start - my_rsv->rsv_end - 1) >= size)
+ my_rsv->rsv_end += size;
+ else
+ my_rsv->rsv_end = next_rsv->rsv_start - 1;
+ }
+ spin_unlock(rsv_lock);
+}
+
+/**
+ * ext4_try_to_allocate_with_rsv()
+ * @sb: superblock
+ * @handle: handle to this transaction
+ * @group: given allocation block group
+ * @bitmap_bh: bufferhead holds the block bitmap
+ * @grp_goal: given target block within the group
+ * @count: target number of blocks to allocate
+ * @my_rsv: reservation window
+ * @errp: pointer to store the error code
+ *
+ * This is the main function used to allocate a new block and its reservation
+ * window.
+ *
+ * Each time when a new block allocation is need, first try to allocate from
+ * its own reservation. If it does not have a reservation window, instead of
+ * looking for a free bit on bitmap first, then look up the reservation list to
+ * see if it is inside somebody else's reservation window, we try to allocate a
+ * reservation window for it starting from the goal first. Then do the block
+ * allocation within the reservation window.
+ *
+ * This will avoid keeping on searching the reservation list again and
+ * again when somebody is looking for a free block (without
+ * reservation), and there are lots of free blocks, but they are all
+ * being reserved.
+ *
+ * We use a red-black tree for the per-filesystem reservation list.
+ *
+ */
+static ext4_grpblk_t
+ext4_try_to_allocate_with_rsv(struct super_block *sb, handle_t *handle,
+ unsigned int group, struct buffer_head *bitmap_bh,
+ ext4_grpblk_t grp_goal,
+ struct ext4_reserve_window_node * my_rsv,
+ unsigned long *count, int *errp)
+{
+ ext4_fsblk_t group_first_block, group_last_block;
+ ext4_grpblk_t ret = 0;
+ int fatal;
+ unsigned long num = *count;
+
+ *errp = 0;
+
+ /*
+ * Make sure we use undo access for the bitmap, because it is critical
+ * that we do the frozen_data COW on bitmap buffers in all cases even
+ * if the buffer is in BJ_Forget state in the committing transaction.
+ */
+ BUFFER_TRACE(bitmap_bh, "get undo access for new block");
+ fatal = ext4_journal_get_undo_access(handle, bitmap_bh);
+ if (fatal) {
+ *errp = fatal;
+ return -1;
+ }
+
+ /*
+ * we don't deal with reservation when
+ * filesystem is mounted without reservation
+ * or the file is not a regular file
+ * or last attempt to allocate a block with reservation turned on failed
+ */
+ if (my_rsv == NULL ) {
+ ret = ext4_try_to_allocate(sb, handle, group, bitmap_bh,
+ grp_goal, count, NULL);
+ goto out;
+ }
+ /*
+ * grp_goal is a group relative block number (if there is a goal)
+ * 0 <= grp_goal < EXT4_BLOCKS_PER_GROUP(sb)
+ * first block is a filesystem wide block number
+ * first block is the block number of the first block in this group
+ */
+ group_first_block = ext4_group_first_block_no(sb, group);
+ group_last_block = group_first_block + (EXT4_BLOCKS_PER_GROUP(sb) - 1);
+
+ /*
+ * Basically we will allocate a new block from inode's reservation
+ * window.
+ *
+ * We need to allocate a new reservation window, if:
+ * a) inode does not have a reservation window; or
+ * b) last attempt to allocate a block from existing reservation
+ * failed; or
+ * c) we come here with a goal and with a reservation window
+ *
+ * We do not need to allocate a new reservation window if we come here
+ * at the beginning with a goal and the goal is inside the window, or
+ * we don't have a goal but already have a reservation window.
+ * then we could go to allocate from the reservation window directly.
+ */
+ while (1) {
+ if (rsv_is_empty(&my_rsv->rsv_window) || (ret < 0) ||
+ !goal_in_my_reservation(&my_rsv->rsv_window,
+ grp_goal, group, sb)) {
+ if (my_rsv->rsv_goal_size < *count)
+ my_rsv->rsv_goal_size = *count;
+ ret = alloc_new_reservation(my_rsv, grp_goal, sb,
+ group, bitmap_bh);
+ if (ret < 0)
+ break; /* failed */
+
+ if (!goal_in_my_reservation(&my_rsv->rsv_window,
+ grp_goal, group, sb))
+ grp_goal = -1;
+ } else if (grp_goal >= 0) {
+ int curr = my_rsv->rsv_end -
+ (grp_goal + group_first_block) + 1;
+
+ if (curr < *count)
+ try_to_extend_reservation(my_rsv, sb,
+ *count - curr);
+ }
+
+ if ((my_rsv->rsv_start > group_last_block) ||
+ (my_rsv->rsv_end < group_first_block)) {
+ rsv_window_dump(&EXT4_SB(sb)->s_rsv_window_root, 1);
+ BUG();
+ }
+ ret = ext4_try_to_allocate(sb, handle, group, bitmap_bh,
+ grp_goal, &num, &my_rsv->rsv_window);
+ if (ret >= 0) {
+ my_rsv->rsv_alloc_hit += num;
+ *count = num;
+ break; /* succeed */
+ }
+ num = *count;
+ }
+out:
+ if (ret >= 0) {
+ BUFFER_TRACE(bitmap_bh, "journal_dirty_metadata for "
+ "bitmap block");
+ fatal = ext4_journal_dirty_metadata(handle, bitmap_bh);
+ if (fatal) {
+ *errp = fatal;
+ return -1;
+ }
+ return ret;
+ }
+
+ BUFFER_TRACE(bitmap_bh, "journal_release_buffer");
+ ext4_journal_release_buffer(handle, bitmap_bh);
+ return ret;
+}
+
+/**
+ * ext4_has_free_blocks()
+ * @sbi: in-core super block structure.
+ *
+ * Check if filesystem has at least 1 free block available for allocation.
+ */
+static int ext4_has_free_blocks(struct super_block *sb)
+{
+ struct ext4_sb_info *sbi = EXT4_SB(sb);
+ ext4_fsblk_t free_blocks, root_blocks;
+ int cond;
+
+ free_blocks = percpu_counter_read_positive(&sbi->s_freeblocks_counter);
+ root_blocks = ext4_r_blocks_count(sbi->s_es);
+
+ vxdprintk(VXD_CBIT(dlim, 3),
+ "ext4_has_free_blocks(%p): free=%llu, root=%llu",
+ sb, free_blocks, root_blocks);
+
+ DLIMIT_ADJUST_BLOCK(sb, dx_current_tag(), &free_blocks, &root_blocks);
+
+ cond = (free_blocks < root_blocks + 1 &&
+ !capable(CAP_SYS_RESOURCE) &&
+ sbi->s_resuid != current->fsuid &&
+ (sbi->s_resgid == 0 || !in_group_p (sbi->s_resgid)));
+
+ vxdprintk(VXD_CBIT(dlim, 3),
+ "ext4_has_free_blocks(%p): %llu<%llu+1, %c, %u!=%u r=%d",
+ sb, free_blocks, root_blocks,
+ !capable(CAP_SYS_RESOURCE)?'1':'0',
+ sbi->s_resuid, current->fsuid, cond?0:1);
+
+ return (cond ? 0 : 1);
+}
+
+/**
+ * ext4_should_retry_alloc()
+ * @sb: super block
+ * @retries number of attemps has been made
+ *
+ * ext4_should_retry_alloc() is called when ENOSPC is returned, and if
+ * it is profitable to retry the operation, this function will wait
+ * for the current or commiting transaction to complete, and then
+ * return TRUE.
+ *
+ * if the total number of retries exceed three times, return FALSE.
+ */
+int ext4_should_retry_alloc(struct super_block *sb, int *retries)
+{
+ if (!ext4_has_free_blocks(sb) || (*retries)++ > 3)
+ return 0;
+
+ jbd_debug(1, "%s: retrying operation after ENOSPC\n", sb->s_id);
+
+ return jbd2_journal_force_commit_nested(EXT4_SB(sb)->s_journal);
+}
+
+/**
+ * ext4_new_blocks() -- core block(s) allocation function
+ * @handle: handle to this transaction
+ * @inode: file inode
+ * @goal: given target block(filesystem wide)
+ * @count: target number of blocks to allocate
+ * @errp: error code
+ *
+ * ext4_new_blocks uses a goal block to assist allocation. It tries to
+ * allocate block(s) from the block group contains the goal block first. If that
+ * fails, it will try to allocate block(s) from other block groups without
+ * any specific goal block.
+ *
+ */
+ext4_fsblk_t ext4_new_blocks(handle_t *handle, struct inode *inode,
+ ext4_fsblk_t goal, unsigned long *count, int *errp)
+{
+ struct buffer_head *bitmap_bh = NULL;
+ struct buffer_head *gdp_bh;
+ unsigned long group_no;
+ int goal_group;
+ ext4_grpblk_t grp_target_blk; /* blockgroup relative goal block */
+ ext4_grpblk_t grp_alloc_blk; /* blockgroup-relative allocated block*/
+ ext4_fsblk_t ret_block; /* filesyetem-wide allocated block */
+ int bgi; /* blockgroup iteration index */
+ int fatal = 0, err;
+ int performed_allocation = 0;
+ ext4_grpblk_t free_blocks; /* number of free blocks in a group */
+ struct super_block *sb;
+ struct ext4_group_desc *gdp;
+ struct ext4_super_block *es;
+ struct ext4_sb_info *sbi;
+ struct ext4_reserve_window_node *my_rsv = NULL;
+ struct ext4_block_alloc_info *block_i;
+ unsigned short windowsz = 0;
+#ifdef EXT4FS_DEBUG
+ static int goal_hits, goal_attempts;
+#endif
+ unsigned long ngroups;
+ unsigned long num = *count;
+
+ *errp = -ENOSPC;
+ sb = inode->i_sb;
+ if (!sb) {
+ printk("ext4_new_block: nonexistent device");
+ return 0;
+ }
+
+ /*
+ * Check quota for allocation of this block.
+ */
+ if (DQUOT_ALLOC_BLOCK(inode, num)) {
+ *errp = -EDQUOT;
+ return 0;
+ }
+ if (DLIMIT_ALLOC_BLOCK(inode, 1))
+ goto out_dlimit;
+
+ sbi = EXT4_SB(sb);
+ es = EXT4_SB(sb)->s_es;
+ ext4_debug("goal=%lu.\n", goal);
+ /*
+ * Allocate a block from reservation only when
+ * filesystem is mounted with reservation(default,-o reservation), and
+ * it's a regular file, and
+ * the desired window size is greater than 0 (One could use ioctl
+ * command EXT4_IOC_SETRSVSZ to set the window size to 0 to turn off
+ * reservation on that particular file)
+ */
+ block_i = EXT4_I(inode)->i_block_alloc_info;
+ if (block_i && ((windowsz = block_i->rsv_window_node.rsv_goal_size) > 0))
+ my_rsv = &block_i->rsv_window_node;
+
+ if (!ext4_has_free_blocks(sb)) {
+ *errp = -ENOSPC;
+ goto out;
+ }
+
+ /*
+ * First, test whether the goal block is free.
+ */
+ if (goal < le32_to_cpu(es->s_first_data_block) ||
+ goal >= ext4_blocks_count(es))
+ goal = le32_to_cpu(es->s_first_data_block);
+ ext4_get_group_no_and_offset(sb, goal, &group_no, &grp_target_blk);
+ goal_group = group_no;
+retry_alloc:
+ gdp = ext4_get_group_desc(sb, group_no, &gdp_bh);
+ if (!gdp)
+ goto io_error;
+
+ free_blocks = le16_to_cpu(gdp->bg_free_blocks_count);
+ /*
+ * if there is not enough free blocks to make a new resevation
+ * turn off reservation for this allocation
+ */
+ if (my_rsv && (free_blocks < windowsz)
+ && (rsv_is_empty(&my_rsv->rsv_window)))
+ my_rsv = NULL;
+
+ if (free_blocks > 0) {
+ bitmap_bh = read_block_bitmap(sb, group_no);
+ if (!bitmap_bh)
+ goto io_error;
+ grp_alloc_blk = ext4_try_to_allocate_with_rsv(sb, handle,
+ group_no, bitmap_bh, grp_target_blk,
+ my_rsv, &num, &fatal);
+ if (fatal)
+ goto out;
+ if (grp_alloc_blk >= 0)
+ goto allocated;
+ }
+
+ ngroups = EXT4_SB(sb)->s_groups_count;
+ smp_rmb();
+
+ /*
+ * Now search the rest of the groups. We assume that
+ * i and gdp correctly point to the last group visited.
+ */
+ for (bgi = 0; bgi < ngroups; bgi++) {
+ group_no++;
+ if (group_no >= ngroups)
+ group_no = 0;
+ gdp = ext4_get_group_desc(sb, group_no, &gdp_bh);
+ if (!gdp)
+ goto io_error;
+ free_blocks = le16_to_cpu(gdp->bg_free_blocks_count);
+ /*
+ * skip this group if the number of
+ * free blocks is less than half of the reservation
+ * window size.
+ */
+ if (free_blocks <= (windowsz/2))
+ continue;
+
+ brelse(bitmap_bh);
+ bitmap_bh = read_block_bitmap(sb, group_no);
+ if (!bitmap_bh)
+ goto io_error;
+ /*
+ * try to allocate block(s) from this group, without a goal(-1).
+ */
+ grp_alloc_blk = ext4_try_to_allocate_with_rsv(sb, handle,
+ group_no, bitmap_bh, -1, my_rsv,
+ &num, &fatal);
+ if (fatal)
+ goto out;
+ if (grp_alloc_blk >= 0)
+ goto allocated;
+ }
+ /*
+ * We may end up a bogus ealier ENOSPC error due to
+ * filesystem is "full" of reservations, but
+ * there maybe indeed free blocks avaliable on disk
+ * In this case, we just forget about the reservations
+ * just do block allocation as without reservations.
+ */
+ if (my_rsv) {
+ my_rsv = NULL;
+ windowsz = 0;
+ group_no = goal_group;
+ goto retry_alloc;
+ }
+ /* No space left on the device */
+ *errp = -ENOSPC;
+ goto out;
+
+allocated:
+
+ ext4_debug("using block group %d(%d)\n",
+ group_no, gdp->bg_free_blocks_count);
+
+ BUFFER_TRACE(gdp_bh, "get_write_access");
+ fatal = ext4_journal_get_write_access(handle, gdp_bh);
+ if (fatal)
+ goto out;
+
+ ret_block = grp_alloc_blk + ext4_group_first_block_no(sb, group_no);
+
+ if (in_range(ext4_block_bitmap(sb, gdp), ret_block, num) ||
+ in_range(ext4_block_bitmap(sb, gdp), ret_block, num) ||
+ in_range(ret_block, ext4_inode_table(sb, gdp),
+ EXT4_SB(sb)->s_itb_per_group) ||
+ in_range(ret_block + num - 1, ext4_inode_table(sb, gdp),
+ EXT4_SB(sb)->s_itb_per_group))
+ ext4_error(sb, "ext4_new_block",
+ "Allocating block in system zone - "
+ "blocks from %llu, length %lu",
+ ret_block, num);
+
+ performed_allocation = 1;
+
+#ifdef CONFIG_JBD_DEBUG
+ {
+ struct buffer_head *debug_bh;
+
+ /* Record bitmap buffer state in the newly allocated block */
+ debug_bh = sb_find_get_block(sb, ret_block);
+ if (debug_bh) {
+ BUFFER_TRACE(debug_bh, "state when allocated");
+ BUFFER_TRACE2(debug_bh, bitmap_bh, "bitmap state");
+ brelse(debug_bh);
+ }
+ }
+ jbd_lock_bh_state(bitmap_bh);
+ spin_lock(sb_bgl_lock(sbi, group_no));
+ if (buffer_jbd(bitmap_bh) && bh2jh(bitmap_bh)->b_committed_data) {
+ int i;
+
+ for (i = 0; i < num; i++) {
+ if (ext4_test_bit(grp_alloc_blk+i,
+ bh2jh(bitmap_bh)->b_committed_data)) {
+ printk("%s: block was unexpectedly set in "
+ "b_committed_data\n", __FUNCTION__);
+ }
+ }
+ }
+ ext4_debug("found bit %d\n", grp_alloc_blk);
+ spin_unlock(sb_bgl_lock(sbi, group_no));
+ jbd_unlock_bh_state(bitmap_bh);
+#endif
+
+ if (ret_block + num - 1 >= ext4_blocks_count(es)) {
+ ext4_error(sb, "ext4_new_block",
+ "block(%llu) >= blocks count(%llu) - "
+ "block_group = %lu, es == %p ", ret_block,
+ ext4_blocks_count(es), group_no, es);
+ goto out;
+ }
+
+ /*
+ * It is up to the caller to add the new buffer to a journal
+ * list of some description. We don't know in advance whether
+ * the caller wants to use it as metadata or data.
+ */
+ ext4_debug("allocating block %lu. Goal hits %d of %d.\n",
+ ret_block, goal_hits, goal_attempts);
+
+ spin_lock(sb_bgl_lock(sbi, group_no));
+ gdp->bg_free_blocks_count =
+ cpu_to_le16(le16_to_cpu(gdp->bg_free_blocks_count)-num);
+ spin_unlock(sb_bgl_lock(sbi, group_no));
+ percpu_counter_mod(&sbi->s_freeblocks_counter, -num);
+
+ BUFFER_TRACE(gdp_bh, "journal_dirty_metadata for group descriptor");
+ err = ext4_journal_dirty_metadata(handle, gdp_bh);
+ if (!fatal)
+ fatal = err;
+
+ sb->s_dirt = 1;
+ if (fatal)
+ goto out;
+
+ *errp = 0;
+ brelse(bitmap_bh);
+ DQUOT_FREE_BLOCK(inode, *count-num);
+ *count = num;
+ return ret_block;
+
+io_error:
+ *errp = -EIO;
+out:
+ if (!performed_allocation)
+ DLIMIT_FREE_BLOCK(inode, 1);
+out_dlimit:
+ if (fatal) {
+ *errp = fatal;
+ ext4_std_error(sb, fatal);
+ }
+ /*
+ * Undo the block allocation
+ */
+ if (!performed_allocation)
+ DQUOT_FREE_BLOCK(inode, *count);
+ brelse(bitmap_bh);
+ return 0;
+}
+
+ext4_fsblk_t ext4_new_block(handle_t *handle, struct inode *inode,
+ ext4_fsblk_t goal, int *errp)
+{
+ unsigned long count = 1;
+
+ return ext4_new_blocks(handle, inode, goal, &count, errp);
+}
+
+/**
+ * ext4_count_free_blocks() -- count filesystem free blocks
+ * @sb: superblock
+ *
+ * Adds up the number of free blocks from each block group.
+ */
+ext4_fsblk_t ext4_count_free_blocks(struct super_block *sb)
+{
+ ext4_fsblk_t desc_count;
+ struct ext4_group_desc *gdp;
+ int i;
+ unsigned long ngroups = EXT4_SB(sb)->s_groups_count;
+#ifdef EXT4FS_DEBUG
+ struct ext4_super_block *es;
+ ext4_fsblk_t bitmap_count;
+ unsigned long x;
+ struct buffer_head *bitmap_bh = NULL;
+
+ es = EXT4_SB(sb)->s_es;
+ desc_count = 0;
+ bitmap_count = 0;
+ gdp = NULL;
+
+ smp_rmb();
+ for (i = 0; i < ngroups; i++) {
+ gdp = ext4_get_group_desc(sb, i, NULL);
+ if (!gdp)
+ continue;
+ desc_count += le16_to_cpu(gdp->bg_free_blocks_count);
+ brelse(bitmap_bh);
+ bitmap_bh = read_block_bitmap(sb, i);
+ if (bitmap_bh == NULL)
+ continue;
+
+ x = ext4_count_free(bitmap_bh, sb->s_blocksize);
+ printk("group %d: stored = %d, counted = %lu\n",
+ i, le16_to_cpu(gdp->bg_free_blocks_count), x);
+ bitmap_count += x;
+ }
+ brelse(bitmap_bh);
+ printk("ext4_count_free_blocks: stored = %llu"
+ ", computed = %llu, %llu\n",
+ EXT4_FREE_BLOCKS_COUNT(es),
+ desc_count, bitmap_count);
+ return bitmap_count;
+#else
+ desc_count = 0;
+ smp_rmb();
+ for (i = 0; i < ngroups; i++) {
+ gdp = ext4_get_group_desc(sb, i, NULL);
+ if (!gdp)
+ continue;
+ desc_count += le16_to_cpu(gdp->bg_free_blocks_count);
+ }
+
+ return desc_count;
+#endif
+}
+
+static inline int
+block_in_use(ext4_fsblk_t block, struct super_block *sb, unsigned char *map)
+{
+ ext4_grpblk_t offset;
+
+ ext4_get_group_no_and_offset(sb, block, NULL, &offset);
+ return ext4_test_bit (offset, map);
+}
+
+static inline int test_root(int a, int b)
+{
+ int num = b;
+
+ while (a > num)
+ num *= b;
+ return num == a;
+}
+
+static int ext4_group_sparse(int group)
+{
+ if (group <= 1)
+ return 1;
+ if (!(group & 1))
+ return 0;
+ return (test_root(group, 7) || test_root(group, 5) ||
+ test_root(group, 3));
+}
+
+/**
+ * ext4_bg_has_super - number of blocks used by the superblock in group
+ * @sb: superblock for filesystem
+ * @group: group number to check
+ *
+ * Return the number of blocks used by the superblock (primary or backup)
+ * in this group. Currently this will be only 0 or 1.
+ */
+int ext4_bg_has_super(struct super_block *sb, int group)
+{
+ if (EXT4_HAS_RO_COMPAT_FEATURE(sb,
+ EXT4_FEATURE_RO_COMPAT_SPARSE_SUPER) &&
+ !ext4_group_sparse(group))
+ return 0;
+ return 1;
+}
+
+static unsigned long ext4_bg_num_gdb_meta(struct super_block *sb, int group)
+{
+ unsigned long metagroup = group / EXT4_DESC_PER_BLOCK(sb);
+ unsigned long first = metagroup * EXT4_DESC_PER_BLOCK(sb);
+ unsigned long last = first + EXT4_DESC_PER_BLOCK(sb) - 1;
+
+ if (group == first || group == first + 1 || group == last)
+ return 1;
+ return 0;
+}
+
+static unsigned long ext4_bg_num_gdb_nometa(struct super_block *sb, int group)
+{
+ if (EXT4_HAS_RO_COMPAT_FEATURE(sb,
+ EXT4_FEATURE_RO_COMPAT_SPARSE_SUPER) &&
+ !ext4_group_sparse(group))
+ return 0;
+ return EXT4_SB(sb)->s_gdb_count;
+}
+
+/**
+ * ext4_bg_num_gdb - number of blocks used by the group table in group
+ * @sb: superblock for filesystem
+ * @group: group number to check
+ *
+ * Return the number of blocks used by the group descriptor table
+ * (primary or backup) in this group. In the future there may be a
+ * different number of descriptor blocks in each group.
+ */
+unsigned long ext4_bg_num_gdb(struct super_block *sb, int group)
+{
+ unsigned long first_meta_bg =
+ le32_to_cpu(EXT4_SB(sb)->s_es->s_first_meta_bg);
+ unsigned long metagroup = group / EXT4_DESC_PER_BLOCK(sb);
+
+ if (!EXT4_HAS_INCOMPAT_FEATURE(sb,EXT4_FEATURE_INCOMPAT_META_BG) ||
+ metagroup < first_meta_bg)
+ return ext4_bg_num_gdb_nometa(sb,group);
+
+ return ext4_bg_num_gdb_meta(sb,group);
+
+}
git://git.onelab.eu / linux-2.6.git / blobdiff