linux.git/fs/ext4, branch v2.6.29

ext4: fix bb_prealloc_list corruption due to wrong group locking

2009-03-17T03:25:40+00:00

This is for Red Hat bug 490026: EXT4 panic, list corruption in
ext4_mb_new_inode_pa

ext4_lock_group(sb, group) is supposed to protect this list for
each group, and a common code flow to remove an album is like
this:

    ext4_get_group_no_and_offset(sb, pa->pa_pstart, &grp, NULL);
    ext4_lock_group(sb, grp);
    list_del(&pa->pa_group_list);
    ext4_unlock_group(sb, grp);

so it's critical that we get the right group number back for
this prealloc context, to lock the right group (the one 
associated with this pa) and prevent concurrent list manipulation.

however, ext4_mb_put_pa() passes in (pa->pa_pstart - 1) with a 
comment, "-1 is to protect from crossing allocation group".

This makes sense for the group_pa, where pa_pstart is advanced
by the length which has been used (in ext4_mb_release_context()),
and when the entire length has been used, pa_pstart has been
advanced to the first block of the next group.

However, for inode_pa, pa_pstart is never advanced; it's just
set once to the first block in the group and not moved after
that.  So in this case, if we subtract one in ext4_mb_put_pa(),
we are actually locking the *previous* group, and opening the
race with the other threads which do not subtract off the extra
block.

Signed-off-by: Eric Sandeen 
Signed-off-by: "Theodore Ts'o"

ext4: fix bogus BUG_ONs in in mballoc code

2009-03-14T15:51:46+00:00

Thiemo Nagel reported that:

# dd if=/dev/zero of=image.ext4 bs=1M count=2
# mkfs.ext4 -v -F -b 1024 -m 0 -g 512 -G 4 -I 128 -N 1 \
  -O large_file,dir_index,flex_bg,extent,sparse_super image.ext4
# mount -o loop image.ext4 mnt/
# dd if=/dev/zero of=mnt/file

oopsed, with a BUG_ON in ext4_mb_normalize_request because
size == EXT4_BLOCKS_PER_GROUP

It appears to me (esp. after talking to Andreas) that the BUG_ON
is bogus; a request of exactly EXT4_BLOCKS_PER_GROUP should
be allowed, though larger sizes do indicate a problem.

Fix that an another (apparently rare) codepath with a similar check.

Reported-by: Thiemo Nagel 
Signed-off-by: Eric Sandeen 
Signed-off-by: "Theodore Ts'o"

ext4: Print the find_group_flex() warning only once

2009-03-12T16:20:01+00:00

This is a short-term warning, and even printk_ratelimit() can result
in too much noise in system logs.  So only print it once as a warning.

Signed-off-by: "Theodore Ts'o"

ext4: fix header check in ext4_ext_search_right() for deep extent trees.

2009-03-10T22:18:47+00:00

The ext4_ext_search_right() function is confusing; it uses a
"depth" variable which is 0 at the root and maximum at the leaves, 
but the on-disk metadata uses a "depth" (actually eh_depth) which
is opposite: maximum at the root, and 0 at the leaves.

The ext4_ext_check_header() function is given a depth and checks
the header agaisnt that depth; it expects the on-disk semantics,
but we are giving it the opposite in the while loop in this 
function.  We should be giving it the on-disk notion of "depth"
which we can get from (p_depth - depth) - and if you look, the last
(more commonly hit) call to ext4_ext_check_header() does just this.

Sending in the wrong depth results in (incorrect) messages
about corruption:

EXT4-fs error (device sdb1): ext4_ext_search_right: bad header
in inode #2621457: unexpected eh_depth - magic f30a, entries 340,
max 340(0), depth 1(2)

http://bugzilla.kernel.org/show_bug.cgi?id=12821

Reported-by: David Dindorp 
Signed-off-by: Eric Sandeen 
Signed-off-by: "Theodore Ts'o"

ext4: fix ext4_free_inode() vs. ext4_claim_inode() race

2009-03-04T23:38:18+00:00

I was seeing fsck errors on inode bitmaps after a 4 thread
dbench run on a 4 cpu machine:

Inode bitmap differences: -50736 -(50752--50753) etc...

I believe that this is because ext4_free_inode() uses atomic
bitops, and although ext4_new_inode() *used* to also use atomic 
bitops for synchronization, commit 
393418676a7602e1d7d3f6e560159c65c8cbd50e changed this to use
the sb_bgl_lock, so that we could also synchronize against
read_inode_bitmap and initialization of uninit inode tables.

However, that change left ext4_free_inode using atomic bitops,
which I think leaves no synchronization between setting & 
unsetting bits in the inode table.

The below patch fixes it for me, although I wonder if we're 
getting at all heavy-handed with this spinlock...

Signed-off-by: Eric Sandeen 
Reviewed-by: Aneesh Kumar K.V 
Signed-off-by: "Theodore Ts'o"

ext4: don't call jbd2_journal_force_commit_nested without journal

2009-02-26T05:57:35+00:00

Running without a journal, I oopsed when I ran out of space,
because we called jbd2_journal_force_commit_nested() from
ext4_should_retry_alloc() without a journal.

This should take care of it, I think.

Signed-off-by: Eric Sandeen 
Signed-off-by: "Theodore Ts'o"

ext4: Remove duplicate call to ext4_commit_super() in ext4_freeze()

2009-02-28T05:08:53+00:00

Commit c4be0c1d added error checking to ext4_freeze() when calling
ext4_commit_super().  Unfortunately the patch failed to remove the
original call to ext4_commit_super(), with the net result that when
freezing the filesystem, the superblock gets written twice, the first
time without error checking.

Signed-off-by: "Theodore Ts'o"

ext4: Fix deadlock in ext4_write_begin() and ext4_da_write_begin()

2009-02-23T02:09:59+00:00

Functions ext4_write_begin() and ext4_da_write_begin() call
grab_cache_page_write_begin() without AOP_FLAG_NOFS. Thus it
can happen that page reclaim is triggered in that function
and it recurses back into the filesystem (or some other filesystem).
But this can lead to various problems as a transaction is already
started at that point. Add the necessary flag.

http://bugzilla.kernel.org/show_bug.cgi?id=11688

Signed-off-by: Jan Kara 
Signed-off-by: "Theodore Ts'o"

ext4: Add fallback for find_group_flex

2009-02-21T17:13:24+00:00

This is a workaround for find_group_flex() which badly needs to be
replaced.  One of its problems (besides ignoring the Orlov algorithm)
is that it is a bit hyperactive about returning failure under
suspicious circumstances.  This can lead to spurious ENOSPC failures
even when there are inodes still available.

Work around this for now by retrying the search using
find_group_other() if find_group_flex() returns -1.  If
find_group_other() succeeds when find_group_flex() has failed, log a
warning message.

A better block/inode allocator that will fix this problem for real has
been queued up for the next merge window.

Signed-off-by: "Theodore Ts'o"

ext4: Fix NULL dereference in ext4_ext_migrate()'s error handling

2009-02-16T01:02:19+00:00

This was found through a code checker (http://repo.or.cz/w/smatch.git/). 
It looks like you might be able to trigger the error by trying to migrate 
a readonly file system.

Signed-off-by: Dan Carpenter 
Signed-off-by: "Theodore Ts'o"