xfs: rmap btree requires more reserved free space

[deliverable/linux.git] / fs / xfs / libxfs / xfs_alloc.h

diff --git a/fs/xfs/libxfs/xfs_alloc.h b/fs/xfs/libxfs/xfs_alloc.h
index 88053422fda036478aa1c677ee77f323ae0a7677..360f9e42553612867cfe7f196c33a50a6959292c 100644 (file)
--- a/fs/xfs/libxfs/xfs_alloc.h
+++ b/fs/xfs/libxfs/xfs_alloc.h
@@ -55,42 +55,6 @@ typedef unsigned int xfs_alloctype_t;
 #define        XFS_ALLOC_FLAG_TRYLOCK  0x00000001  /* use trylock for buffer locking */
 #define        XFS_ALLOC_FLAG_FREEING  0x00000002  /* indicate caller is freeing extents*/
 
-/*
- * 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 _per AG_, a potential split of file's bmap
- * btree requires 1 fsb, so we set the number of set-aside blocks
- * to 4 + 4*agcount.
- */
-#define XFS_ALLOC_SET_ASIDE(mp)  (4 + ((mp)->m_sb.sb_agcount * 4))
-
-/*
- * When deciding how much space to allocate out of an AG, we limit the
- * allocation maximum size to the size the AG. However, we cannot use all the
- * blocks in the AG - some are permanently used by metadata. These
- * blocks are generally:
- *     - the AG superblock, AGF, AGI and AGFL
- *     - the AGF (bno and cnt) and AGI btree root blocks
- *     - 4 blocks on the AGFL according to XFS_ALLOC_SET_ASIDE() limits
- *
- * The AG headers are sector sized, so the amount of space they take up is
- * dependent on filesystem geometry. The others are all single blocks.
- */
-#define XFS_ALLOC_AG_MAX_USABLE(mp)    \
-       ((mp)->m_sb.sb_agblocks - XFS_BB_TO_FSB(mp, XFS_FSS_TO_BB(mp, 4)) - 7)
-
-
 /*
  * Argument structure for xfs_alloc routines.
  * This is turned into a structure to avoid having 20 arguments passed
@@ -133,6 +97,11 @@ typedef struct xfs_alloc_arg {
 #define XFS_ALLOC_INITIAL_USER_DATA    (1 << 1)/* special case start of file */
 #define XFS_ALLOC_USERDATA_ZERO                (1 << 2)/* zero extent on allocation */
 
+/* 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);
+
 xfs_extlen_t xfs_alloc_longest_free_extent(struct xfs_mount *mp,
                struct xfs_perag *pag, xfs_extlen_t need);
 unsigned int xfs_alloc_min_freelist(struct xfs_mount *mp,