We don't need to take the alloc_sem lock when we
are adding new group. mballoc won't see the new
group added untill we bump sbi->s_groups_count.
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxxxxxxxxxx>
---
fs/ext4/mballoc.c | 7 +++++--
fs/ext4/resize.c | 6 +-----
2 files changed, 6 insertions(+), 7 deletions(-)
diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
index 4ed869e..97b2d89 100644
--- a/fs/ext4/mballoc.c
+++ b/fs/ext4/mballoc.c
@@ -926,8 +926,11 @@ 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 68b0351..4135974 100644
--- a/fs/ext4/resize.c
+++ b/fs/ext4/resize.c
@@ -856,7 +856,6 @@ 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 +874,8 @@ 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 +917,6 @@ 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);
--
1.6.4.2.253.g0b1fac
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