diff options
Diffstat (limited to 'fs/xfs/xfs_mount.c')
| -rw-r--r-- | fs/xfs/xfs_mount.c | 24 |
1 files changed, 22 insertions, 2 deletions
diff --git a/fs/xfs/xfs_mount.c b/fs/xfs/xfs_mount.c index c0b1c2906880..4b7be49cc4de 100644 --- a/fs/xfs/xfs_mount.c +++ b/fs/xfs/xfs_mount.c @@ -1254,6 +1254,26 @@ xfs_mod_sb(xfs_trans_t *tp, __int64_t fields) xfs_trans_log_buf(tp, bp, first, last); } + +/* + * In order to avoid ENOSPC-related deadlock caused by + * out-of-order locking of AGF buffer (PV 947395), we place + * constraints on the relationship among actual allocations for + * data blocks, freelist blocks, and potential file data bmap + * btree blocks. However, these restrictions may result in no + * actual space allocated for a delayed extent, for example, a data + * block in a certain AG is allocated but there is no additional + * block for the additional bmap btree block due to a split of the + * bmap btree of the file. The result of this may lead to an + * infinite loop in xfssyncd when the file gets flushed to disk and + * all delayed extents need to be actually allocated. To get around + * this, we explicitly set aside a few blocks which will not be + * reserved in delayed allocation. Considering the minimum number of + * needed freelist blocks is 4 fsbs, a potential split of file's bmap + * btree requires 1 fsb, so we set the number of set-aside blocks to 8. +*/ +#define SET_ASIDE_BLOCKS 8 + /* * xfs_mod_incore_sb_unlocked() is a utility routine common used to apply * a delta to a specified field in the in-core superblock. Simply @@ -1298,7 +1318,7 @@ xfs_mod_incore_sb_unlocked(xfs_mount_t *mp, xfs_sb_field_t field, return 0; case XFS_SBS_FDBLOCKS: - lcounter = (long long)mp->m_sb.sb_fdblocks; + lcounter = (long long)mp->m_sb.sb_fdblocks - SET_ASIDE_BLOCKS; res_used = (long long)(mp->m_resblks - mp->m_resblks_avail); if (delta > 0) { /* Putting blocks back */ @@ -1332,7 +1352,7 @@ xfs_mod_incore_sb_unlocked(xfs_mount_t *mp, xfs_sb_field_t field, } } - mp->m_sb.sb_fdblocks = lcounter; + mp->m_sb.sb_fdblocks = lcounter + SET_ASIDE_BLOCKS; return 0; case XFS_SBS_FREXTENTS: lcounter = (long long)mp->m_sb.sb_frextents; |