Creating many small files in rapid succession on a small
filesystem can lead to spurious ENOSPC; on a 104MB filesystem:
for i in `seq 1 22500`; do
echo -n > $SCRATCH_MNT/$i
echo XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX > $SCRATCH_MNT/$i
done
leads to ENOSPC even though after a sync, 40% of the fs is free
again.
This is because we reserve worst-case metadata for delalloc writes,
and when data is allocated that worst-case reservation was not
needed.
I've added 2 flushers here:
* when free space is low compared to dirty blocks, do an async flush
* when we get a hard ENOSPC, do a sync flush before retry
This resolves the testcase for me, and survives all 4 generic
ENOSPC tests in xfstests.
V2: don't try to sync if we're still in a (probably nested) transaction.
Thanks to Josef for pointing out that possibility.
Signed-off-by: Eric Sandeen <sandeen@xxxxxxxxxx>
---
diff --git a/fs/ext4/balloc.c b/fs/ext4/balloc.c
index 1d04189..28bde58 100644
--- a/fs/ext4/balloc.c
+++ b/fs/ext4/balloc.c
@@ -605,11 +605,27 @@ int ext4_claim_free_blocks(struct ext4_sb_info *sbi,
*/
int ext4_should_retry_alloc(struct super_block *sb, int *retries)
{
- if (!ext4_has_free_blocks(EXT4_SB(sb), 1) ||
+ s64 dirtyblocks = 0;
+ struct percpu_counter *dbc = &EXT4_SB(sb)->s_dirtyblocks_counter;
+
+ if (test_opt(sb, DELALLOC))
+ dirtyblocks = percpu_counter_read_positive(dbc);
+
+ if ((!ext4_has_free_blocks(EXT4_SB(sb), 1) && !dirtyblocks) ||
(*retries)++ > 3 ||
!EXT4_SB(sb)->s_journal)
return 0;
+ /* try a sync to flush delalloc space & free resvd metadata */
+ if (!ext4_has_free_blocks(EXT4_SB(sb), 1) && dirtyblocks) {
+ if (!ext4_journal_current_handle()) {
+ down_read(&sb->s_umount);
+ sync_inodes_sb(sb);
+ up_read(&sb->s_umount);
+ return 1;
+ }
+ }
+
jbd_debug(1, "%s: retrying operation after ENOSPC\n", sb->s_id);
return jbd2_journal_force_commit_nested(EXT4_SB(sb)->s_journal);
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 5c5bc5d..27c8b9b 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -3024,11 +3024,18 @@ static int ext4_nonda_switch(struct super_block *sb)
if (2 * free_blocks < 3 * dirty_blocks ||
free_blocks < (dirty_blocks + EXT4_FREEBLOCKS_WATERMARK)) {
/*
- * free block count is less that 150% of dirty blocks
- * or free blocks is less that watermark
+ * free block count is less than 150% of dirty blocks
+ * or free blocks is less than watermark
*/
return 1;
}
+ /*
+ * Even if we don't switch but are nearing capacity,
+ * start pushing delalloc when 1/2 of free blocks are dirty.
+ */
+ if (free_blocks < 2 * dirty_blocks)
+ writeback_inodes_sb(sb);
+
return 0;
}
--
To unsubscribe from this list: send the line "unsubscribe linux-ext4" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
