+/* Read data from quotafile - avoid pagecache and such because we cannot afford
+ * acquiring the locks... As quota files are never truncated and quota code
+ * itself serializes the operations (and noone else should touch the files)
+ * we don't have to be afraid of races */
+static ssize_t ext3_quota_read(struct super_block *sb, int type, char *data,
+ size_t len, loff_t off)
+{
+ struct inode *inode = sb_dqopt(sb)->files[type];
+ sector_t blk = off >> EXT3_BLOCK_SIZE_BITS(sb);
+ int err = 0;
+ int offset = off & (sb->s_blocksize - 1);
+ int tocopy;
+ size_t toread;
+ struct buffer_head *bh;
+ loff_t i_size = i_size_read(inode);
+
+ if (off > i_size)
+ return 0;
+ if (off+len > i_size)
+ len = i_size-off;
+ toread = len;
+ while (toread > 0) {
+ tocopy = sb->s_blocksize - offset < toread ?
+ sb->s_blocksize - offset : toread;
+ bh = ext3_bread(NULL, inode, blk, 0, &err);
+ if (err)
+ return err;
+ if (!bh) /* A hole? */
+ memset(data, 0, tocopy);
+ else
+ memcpy(data, bh->b_data+offset, tocopy);
+ brelse(bh);
+ offset = 0;
+ toread -= tocopy;
+ data += tocopy;
+ blk++;
+ }
+ return len;
+}
+
+/* Write to quotafile (we know the transaction is already started and has
+ * enough credits) */
+static ssize_t ext3_quota_write(struct super_block *sb, int type,
+ const char *data, size_t len, loff_t off)
+{
+ struct inode *inode = sb_dqopt(sb)->files[type];
+ sector_t blk = off >> EXT3_BLOCK_SIZE_BITS(sb);
+ int err = 0;
+ int offset = off & (sb->s_blocksize - 1);
+ int tocopy;
+ int journal_quota = EXT3_SB(sb)->s_qf_names[type] != NULL;
+ size_t towrite = len;
+ struct buffer_head *bh;
+ handle_t *handle = journal_current_handle();
+
+ down(&inode->i_sem);
+ while (towrite > 0) {
+ tocopy = sb->s_blocksize - offset < towrite ?
+ sb->s_blocksize - offset : towrite;
+ bh = ext3_bread(handle, inode, blk, 1, &err);
+ if (!bh)
+ goto out;
+ if (journal_quota) {
+ err = ext3_journal_get_write_access(handle, bh);
+ if (err) {
+ brelse(bh);
+ goto out;
+ }
+ }
+ lock_buffer(bh);
+ memcpy(bh->b_data+offset, data, tocopy);
+ flush_dcache_page(bh->b_page);
+ unlock_buffer(bh);
+ if (journal_quota)
+ err = ext3_journal_dirty_metadata(handle, bh);
+ else {
+ /* Always do at least ordered writes for quotas */
+ err = ext3_journal_dirty_data(handle, bh);
+ mark_buffer_dirty(bh);
+ }
+ brelse(bh);
+ if (err)
+ goto out;
+ offset = 0;
+ towrite -= tocopy;
+ data += tocopy;
+ blk++;
+ }
+out:
+ if (len == towrite)
+ return err;
+ if (inode->i_size < off+len-towrite) {
+ i_size_write(inode, off+len-towrite);
+ EXT3_I(inode)->i_disksize = inode->i_size;
+ }
+ inode->i_version++;
+ inode->i_mtime = inode->i_ctime = CURRENT_TIME;
+ ext3_mark_inode_dirty(handle, inode);
+ up(&inode->i_sem);
+ return len - towrite;
+}
+