@@ -150,6 +150,8 @@ enum SHIFT_DIRECTION {
#define EXT4_MB_USE_ROOT_BLOCKS 0x1000
/* Use blocks from reserved pool */
#define EXT4_MB_USE_RESERVED 0x2000
+/* Do strict check for free blocks while retrying block allocation */
+#define EXT4_MB_STRICT_CHECK 0x4000
struct ext4_allocation_request {
/* target inode for block we're allocating */
@@ -2176,9 +2176,13 @@ static int ext4_mb_good_group_nolock(struct ext4_allocation_context *ac,
ext4_group_t group, int cr)
{
struct ext4_group_info *grp = ext4_get_group_info(ac->ac_sb, group);
+ struct super_block *sb = ac->ac_sb;
+ bool should_lock = ac->ac_flags & EXT4_MB_STRICT_CHECK;
ext4_grpblk_t free;
int ret = 0;
+ if (should_lock)
+ ext4_lock_group(sb, group);
free = grp->bb_free;
if (free == 0)
goto out;
@@ -2186,6 +2190,8 @@ static int ext4_mb_good_group_nolock(struct ext4_allocation_context *ac,
goto out;
if (unlikely(EXT4_MB_GRP_BBITMAP_CORRUPT(grp)))
goto out;
+ if (should_lock)
+ ext4_unlock_group(sb, group);
/* We only do this if the grp has never been initialized */
if (unlikely(EXT4_MB_GRP_NEED_INIT(grp))) {
@@ -2194,8 +2200,12 @@ static int ext4_mb_good_group_nolock(struct ext4_allocation_context *ac,
return ret;
}
+ if (should_lock)
+ ext4_lock_group(sb, group);
ret = ext4_mb_good_group(ac, group, cr);
out:
+ if (should_lock)
+ ext4_unlock_group(sb, group);
return ret;
}
@@ -4610,7 +4620,8 @@ static bool ext4_mb_discard_preallocations_should_retry(struct super_block *sb,
goto out_dbg;
}
seq_retry = ext4_get_discard_pa_seq_sum();
- if (seq_retry != *seq) {
+ if (!(ac->ac_flags & EXT4_MB_STRICT_CHECK) || seq_retry != *seq) {
+ ac->ac_flags |= EXT4_MB_STRICT_CHECK;
*seq = seq_retry;
ret = true;
}
@@ -35,7 +35,8 @@ struct partial_cluster;
{ EXT4_MB_DELALLOC_RESERVED, "DELALLOC_RESV" }, \
{ EXT4_MB_STREAM_ALLOC, "STREAM_ALLOC" }, \
{ EXT4_MB_USE_ROOT_BLOCKS, "USE_ROOT_BLKS" }, \
- { EXT4_MB_USE_RESERVED, "USE_RESV" })
+ { EXT4_MB_USE_RESERVED, "USE_RESV" }, \
+ { EXT4_MB_STRICT_CHECK, "STRICT_CHECK" })
#define show_map_flags(flags) __print_flags(flags, "|", \
{ EXT4_GET_BLOCKS_CREATE, "CREATE" }, \
Currently while doing block allocation grp->bb_free may be getting modified if discard is happening in parallel. For e.g. consider a case where there are lot of threads who have preallocated lot of blocks and there is a thread which is trying to discard all of this group's PA. Now it could happen that we see all of those group's bb_free is zero and fail the allocation while there is sufficient space if we free up all the PA. So this patch adds another flag "EXT4_MB_STRICT_CHECK" which will be set if we are unable to allocate any blocks in the first try (since we may not have considered blocks about to be discarded from PA lists). So during retry attempt to allocate blocks we will use ext4_lock_group() for checking if the group is good or not. Signed-off-by: Ritesh Harjani <riteshh@linux.ibm.com> --- fs/ext4/ext4.h | 2 ++ fs/ext4/mballoc.c | 13 ++++++++++++- include/trace/events/ext4.h | 3 ++- 3 files changed, 16 insertions(+), 2 deletions(-)