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| author | Eric Sandeen <sandeen@redhat.com> | 2009-03-04 18:38:18 -0500 |
|---|---|---|
| committer | Theodore Ts'o <tytso@mit.edu> | 2009-03-04 18:38:18 -0500 |
| commit | 7ce9d5d1f3c8736511daa413c64985a05b2feee3 (patch) | |
| tree | 89b30c50d6e09467f43f4f824d04838e9bb33026 /fs/ext4 | |
| parent | fec6c6fec3e20637bee5d276fb61dd8b49a3f9cc (diff) | |
| download | lwn-7ce9d5d1f3c8736511daa413c64985a05b2feee3.tar.gz lwn-7ce9d5d1f3c8736511daa413c64985a05b2feee3.zip | |
ext4: fix ext4_free_inode() vs. ext4_claim_inode() race
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 <sandeen@redhat.com>
Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Diffstat (limited to 'fs/ext4')
| -rw-r--r-- | fs/ext4/ialloc.c | 8 |
1 files changed, 5 insertions, 3 deletions
diff --git a/fs/ext4/ialloc.c b/fs/ext4/ialloc.c index f18a919be70b..627f8c3337a3 100644 --- a/fs/ext4/ialloc.c +++ b/fs/ext4/ialloc.c @@ -188,7 +188,7 @@ void ext4_free_inode(handle_t *handle, struct inode *inode) struct ext4_group_desc *gdp; struct ext4_super_block *es; struct ext4_sb_info *sbi; - int fatal = 0, err, count; + int fatal = 0, err, count, cleared; ext4_group_t flex_group; if (atomic_read(&inode->i_count) > 1) { @@ -248,8 +248,10 @@ void ext4_free_inode(handle_t *handle, struct inode *inode) goto error_return; /* Ok, now we can actually update the inode bitmaps.. */ - if (!ext4_clear_bit_atomic(sb_bgl_lock(sbi, block_group), - bit, bitmap_bh->b_data)) + spin_lock(sb_bgl_lock(sbi, block_group)); + cleared = ext4_clear_bit(bit, bitmap_bh->b_data); + spin_unlock(sb_bgl_lock(sbi, block_group)); + if (!cleared) ext4_error(sb, "ext4_free_inode", "bit already cleared for inode %lu", ino); else { |