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| author | Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> | 2009-09-09 23:34:50 -0400 |
|---|---|---|
| committer | Theodore Ts'o <tytso@mit.edu> | 2009-09-09 23:34:50 -0400 |
| commit | f41c0750538667b87a19c93952e5d42fcc069bd7 (patch) | |
| tree | 042076950064d1201e7e408aba0e96ccbd7e00e2 /fs | |
| parent | b6a758ec3af3ec236dbfdcf6a06b84ac8f94957e (diff) | |
| download | linux-f41c0750538667b87a19c93952e5d42fcc069bd7.tar.gz linux-f41c0750538667b87a19c93952e5d42fcc069bd7.tar.bz2 linux-f41c0750538667b87a19c93952e5d42fcc069bd7.zip | |
ext4: check for need init flag in ext4_mb_load_buddy
We should check for need init flag with the group's alloc_sem held, to
make sure while we are loading the buddy cache and holding a reference
to it, a file system resize can't add new blocks to same group.
The patch also drops the need init flag check in
ext4_mb_regular_allocator() because doing the check without holding
alloc_sem is racy.
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Diffstat (limited to 'fs')
| -rw-r--r-- | fs/ext4/mballoc.c | 39 |
1 files changed, 18 insertions, 21 deletions
diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c index fed5ac699141..484c9d10c7fa 100644 --- a/fs/ext4/mballoc.c +++ b/fs/ext4/mballoc.c @@ -1034,8 +1034,26 @@ ext4_mb_load_buddy(struct super_block *sb, ext4_group_t group, * groups mapped by the page is blocked * till we are done with allocation */ +repeat_load_buddy: down_read(e4b->alloc_semp); + if (unlikely(EXT4_MB_GRP_NEED_INIT(grp))) { + /* we need to check for group need init flag + * with alloc_semp held so that we can be sure + * that new blocks didn't get added to the group + * when we are loading the buddy cache + */ + up_read(e4b->alloc_semp); + /* + * we need full data about the group + * to make a good selection + */ + ret = ext4_mb_init_group(sb, group); + if (ret) + return ret; + goto repeat_load_buddy; + } + /* * the buddy cache inode stores the block bitmap * and buddy information in consecutive blocks. @@ -2012,27 +2030,6 @@ repeat: if (grp->bb_free == 0) continue; - /* - * if the group is already init we check whether it is - * a good group and if not we don't load the buddy - */ - if (EXT4_MB_GRP_NEED_INIT(grp)) { - /* - * we need full data about the group - * to make a good selection - */ - err = ext4_mb_init_group(sb, group); - if (err) - goto out; - } - - /* - * If the particular group doesn't satisfy our - * criteria we continue with the next group - */ - if (!ext4_mb_good_group(ac, group, cr)) - continue; - err = ext4_mb_load_buddy(sb, group, &e4b); if (err) goto out; |