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ext4: Fix ext4_quota_write cross block boundary behaviour

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We always assume what dquot update result in changes in one data block
But ext4_quota_write() function may handle cross block boundary writes
In fact if this ever happen it will result in incorrect journal
credits reservation, and later a BUG_ON.  As soon this never happen
the boundary cross loop is NOOP.  In order to make things straight
let's remove this loop and assert cross boundary condition.

Signed-off-by: Dmitry Monakhov <dmonakhov@openvz.org>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
This commit is contained in:
Dmitry Monakhov 2010-03-02 08:08:51 -05:00 • committed by Theodore Ts'o
parent 273df556b6
commit 67eeb5685d
1 changed files with 37 additions and 38 deletions
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75
fs/ext4/super.c
View file

@ -4010,9 +4010,7 @@ static ssize_t ext4_quota_write(struct super_block *sb, int type,
ext4_lblk_t blk = off >> EXT4_BLOCK_SIZE_BITS(sb);
int err = 0;
int offset = off & (sb->s_blocksize - 1);
int tocopy;
int journal_quota = EXT4_SB(sb)->s_qf_names[type] != NULL;
size_t towrite = len;
struct buffer_head *bh;
handle_t *handle = journal_current_handle();
@ -4022,52 +4020,53 @@ static ssize_t ext4_quota_write(struct super_block *sb, int type,
(unsigned long long)off, (unsigned long long)len);
return -EIO;
}
mutex_lock_nested(&inode->i_mutex, I_MUTEX_QUOTA);
while (towrite > 0) {
tocopy = sb->s_blocksize - offset < towrite ?
sb->s_blocksize - offset : towrite;
bh = ext4_bread(handle, inode, blk, 1, &err);
if (!bh)
goto out;
if (journal_quota) {
err = ext4_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 = ext4_handle_dirty_metadata(handle, NULL, bh);
else {
/* Always do at least ordered writes for quotas */
err = ext4_jbd2_file_inode(handle, inode);
mark_buffer_dirty(bh);
}
brelse(bh);
if (err)
goto out;
offset = 0;
towrite -= tocopy;
data += tocopy;
blk++;
/*
* Since we account only one data block in transaction credits,
* then it is impossible to cross a block boundary.
*/
if (sb->s_blocksize - offset < len) {
ext4_msg(sb, KERN_WARNING, "Quota write (off=%llu, len=%llu)"
" cancelled because not block aligned",
(unsigned long long)off, (unsigned long long)len);
return -EIO;
}
mutex_lock_nested(&inode->i_mutex, I_MUTEX_QUOTA);
bh = ext4_bread(handle, inode, blk, 1, &err);
if (!bh)
goto out;
if (journal_quota) {
err = ext4_journal_get_write_access(handle, bh);
if (err) {
brelse(bh);
goto out;
}
}
lock_buffer(bh);
memcpy(bh->b_data+offset, data, len);
flush_dcache_page(bh->b_page);
unlock_buffer(bh);
if (journal_quota)
err = ext4_handle_dirty_metadata(handle, NULL, bh);
else {
/* Always do at least ordered writes for quotas */
err = ext4_jbd2_file_inode(handle, inode);
mark_buffer_dirty(bh);
}
brelse(bh);
out:
if (len == towrite) {
if (err) {
mutex_unlock(&inode->i_mutex);
return err;
}
if (inode->i_size < off+len-towrite) {
i_size_write(inode, off+len-towrite);
if (inode->i_size < off + len) {
i_size_write(inode, off + len);
EXT4_I(inode)->i_disksize = inode->i_size;
}
inode->i_mtime = inode->i_ctime = CURRENT_TIME;
ext4_mark_inode_dirty(handle, inode);
mutex_unlock(&inode->i_mutex);
return len - towrite;
return len;
}
#endif