diff options
-rw-r--r-- | fs/xfs/libxfs/xfs_alloc.c | 28 | ||||
-rw-r--r-- | fs/xfs/libxfs/xfs_alloc.h | 1 |
2 files changed, 23 insertions, 6 deletions
diff --git a/fs/xfs/libxfs/xfs_alloc.c b/fs/xfs/libxfs/xfs_alloc.c index 353e53b892e6..b52ed339727f 100644 --- a/fs/xfs/libxfs/xfs_alloc.c +++ b/fs/xfs/libxfs/xfs_alloc.c @@ -82,6 +82,24 @@ xfs_prealloc_blocks( } /* + * The number of blocks per AG that we withhold from xfs_mod_fdblocks to + * guarantee that we can refill the AGFL prior to allocating space in a nearly + * full AG. Although the the space described by the free space btrees, the + * blocks used by the freesp btrees themselves, and the blocks owned by the + * AGFL are counted in the ondisk fdblocks, it's a mistake to let the ondisk + * free space in the AG drop so low that the free space btrees cannot refill an + * empty AGFL up to the minimum level. Rather than grind through empty AGs + * until the fs goes down, we subtract this many AG blocks from the incore + * fdblocks to ensure user allocation does not overcommit the space the + * filesystem needs for the AGFLs. The rmap btree uses a per-AG reservation to + * withhold space from xfs_mod_fdblocks, so we do not account for that here. + */ +#define XFS_ALLOCBT_AGFL_RESERVE 4 + +/* + * Compute the number of blocks that we set aside to guarantee the ability to + * refill the AGFL and handle a full bmap btree split. + * * 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 @@ -93,14 +111,14 @@ xfs_prealloc_blocks( * 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. * - * We need to reserve 4 fsbs _per AG_ for the freelist and 4 more to handle a - * potential split of the file's bmap btree. + * For each AG, we need to reserve enough blocks to replenish a totally empty + * AGFL and 4 more to handle a potential split of the file's bmap btree. */ unsigned int xfs_alloc_set_aside( struct xfs_mount *mp) { - return mp->m_sb.sb_agcount * (XFS_ALLOC_AGFL_RESERVE + 4); + return mp->m_sb.sb_agcount * (XFS_ALLOCBT_AGFL_RESERVE + 4); } /* @@ -124,12 +142,12 @@ xfs_alloc_ag_max_usable( unsigned int blocks; blocks = XFS_BB_TO_FSB(mp, XFS_FSS_TO_BB(mp, 4)); /* ag headers */ - blocks += XFS_ALLOC_AGFL_RESERVE; + blocks += XFS_ALLOCBT_AGFL_RESERVE; blocks += 3; /* AGF, AGI btree root blocks */ if (xfs_has_finobt(mp)) blocks++; /* finobt root block */ if (xfs_has_rmapbt(mp)) - blocks++; /* rmap root block */ + blocks++; /* rmap root block */ if (xfs_has_reflink(mp)) blocks++; /* refcount root block */ diff --git a/fs/xfs/libxfs/xfs_alloc.h b/fs/xfs/libxfs/xfs_alloc.h index 1c14a0b1abea..d4c057b764f9 100644 --- a/fs/xfs/libxfs/xfs_alloc.h +++ b/fs/xfs/libxfs/xfs_alloc.h @@ -88,7 +88,6 @@ typedef struct xfs_alloc_arg { #define XFS_ALLOC_NOBUSY (1 << 2)/* Busy extents not allowed */ /* freespace limit calculations */ -#define XFS_ALLOC_AGFL_RESERVE 4 unsigned int xfs_alloc_set_aside(struct xfs_mount *mp); unsigned int xfs_alloc_ag_max_usable(struct xfs_mount *mp); |