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| author | Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> | 2009-09-09 23:50:17 -0400 |
|---|---|---|
| committer | Theodore Ts'o <tytso@mit.edu> | 2009-09-09 23:50:17 -0400 |
| commit | 08c3a8133810d955d97f7146c50c43e4073f2148 (patch) | |
| tree | 7caab5e454cdfc39817bd34b9a5be21743af5771 | |
| parent | f41c0750538667b87a19c93952e5d42fcc069bd7 (diff) | |
| download | linux-stable-08c3a8133810d955d97f7146c50c43e4073f2148.tar.gz linux-stable-08c3a8133810d955d97f7146c50c43e4073f2148.tar.bz2 linux-stable-08c3a8133810d955d97f7146c50c43e4073f2148.zip | |
ext4: Clarify the locking details in mballoc
We don't need to take the alloc_sem lock when we are adding new
groups, since mballoc won't see the new group added until we bump
sbi->s_groups_count.
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
| -rw-r--r-- | fs/ext4/mballoc.c | 7 | ||||
| -rw-r--r-- | fs/ext4/resize.c | 7 |
2 files changed, 6 insertions, 8 deletions
diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c index 484c9d10c7fa..d23056d375b3 100644 --- a/fs/ext4/mballoc.c +++ b/fs/ext4/mballoc.c @@ -928,8 +928,11 @@ int ext4_mb_init_group(struct super_block *sb, ext4_group_t group) blocks_per_page = PAGE_CACHE_SIZE / sb->s_blocksize; this_grp = ext4_get_group_info(sb, group); /* - * This ensures we don't add group - * to this buddy cache via resize + * This ensures that we don't reinit the buddy cache + * page which map to the group from which we are already + * allocating. If we are looking at the buddy cache we would + * have taken a reference using ext4_mb_load_buddy and that + * would have taken the alloc_sem lock. */ num_grp_locked = ext4_mb_get_buddy_cache_lock(sb, group); if (!EXT4_MB_GRP_NEED_INIT(this_grp)) { diff --git a/fs/ext4/resize.c b/fs/ext4/resize.c index 68b0351fc647..3cfc343c41b5 100644 --- a/fs/ext4/resize.c +++ b/fs/ext4/resize.c @@ -746,7 +746,6 @@ int ext4_group_add(struct super_block *sb, struct ext4_new_group_data *input) struct inode *inode = NULL; handle_t *handle; int gdb_off, gdb_num; - int num_grp_locked = 0; int err, err2; gdb_num = input->group / EXT4_DESC_PER_BLOCK(sb); @@ -856,7 +855,6 @@ int ext4_group_add(struct super_block *sb, struct ext4_new_group_data *input) * using the new disk blocks. */ - num_grp_locked = ext4_mb_get_buddy_cache_lock(sb, input->group); /* Update group descriptor block for new group */ gdp = (struct ext4_group_desc *)((char *)primary->b_data + gdb_off * EXT4_DESC_SIZE(sb)); @@ -875,10 +873,8 @@ int ext4_group_add(struct super_block *sb, struct ext4_new_group_data *input) * descriptor */ err = ext4_mb_add_groupinfo(sb, input->group, gdp); - if (err) { - ext4_mb_put_buddy_cache_lock(sb, input->group, num_grp_locked); + if (err) goto exit_journal; - } /* * Make the new blocks and inodes valid next. We do this before @@ -920,7 +916,6 @@ int ext4_group_add(struct super_block *sb, struct ext4_new_group_data *input) /* Update the global fs size fields */ sbi->s_groups_count++; - ext4_mb_put_buddy_cache_lock(sb, input->group, num_grp_locked); ext4_handle_dirty_metadata(handle, NULL, primary); |