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ext4: lock block groups when initializing

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I noticed when filling a 1T filesystem with 4 threads using the
fs_mark benchmark:

fs_mark -d /mnt/test -D 256 -n 100000 -t 4 -s 20480 -F -S 0

that I occasionally got checksum mismatch errors:

EXT4-fs error (device sdb): ext4_init_inode_bitmap: Checksum bad for group 6935

etc.  I'd reliably get 4-5 of them during the run.

It appears that the problem is likely a race to init the bg's
when the uninit_bg feature is enabled.

With the patch below, which adds sb_bgl_locking around initialization,
I was able to complete several runs with no errors or warnings.

Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
This commit is contained in:
Eric Sandeen
2008-08-02 21:21:08 -04:00
committed by Theodore Ts'o
parent e29d1cde63
commit b5f10eed81
4 changed files with 12 additions and 1 deletions
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3
fs/ext4/mballoc.c
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@ -787,13 +787,16 @@ static int ext4_mb_init_cache(struct page *page, char *incore)
if (bh_uptodate_or_lock(bh[i]))
continue;
spin_lock(sb_bgl_lock(EXT4_SB(sb), first_group + i));
if (desc->bg_flags & cpu_to_le16(EXT4_BG_BLOCK_UNINIT)) {
ext4_init_block_bitmap(sb, bh[i],
first_group + i, desc);
set_buffer_uptodate(bh[i]);
unlock_buffer(bh[i]);
spin_unlock(sb_bgl_lock(EXT4_SB(sb), first_group + i));
continue;
}
spin_unlock(sb_bgl_lock(EXT4_SB(sb), first_group + i));
get_bh(bh[i]);
bh[i]->b_end_io = end_buffer_read_sync;
submit_bh(READ, bh[i]);