diff options
Diffstat (limited to 'fs/xfs/libxfs/xfs_shared.h')
| -rw-r--r-- | fs/xfs/libxfs/xfs_shared.h | 12 |
1 files changed, 12 insertions, 0 deletions
diff --git a/fs/xfs/libxfs/xfs_shared.h b/fs/xfs/libxfs/xfs_shared.h index 22089f1c880a..1c5debe748f0 100644 --- a/fs/xfs/libxfs/xfs_shared.h +++ b/fs/xfs/libxfs/xfs_shared.h @@ -64,6 +64,18 @@ void xfs_log_get_max_trans_res(struct xfs_mount *mp, #define XFS_TRANS_RESERVE 0x20 /* OK to use reserved data blocks */ #define XFS_TRANS_NO_WRITECOUNT 0x40 /* do not elevate SB writecount */ #define XFS_TRANS_NOFS 0x80 /* pass KM_NOFS to kmem_alloc */ +/* + * LOWMODE is used by the allocator to activate the lowspace algorithm - when + * free space is running low the extent allocator may choose to allocate an + * extent from an AG without leaving sufficient space for a btree split when + * inserting the new extent. In this case the allocator will enable the + * lowspace algorithm which is supposed to allow further allocations (such as + * btree splits and newroots) to allocate from sequential AGs. In order to + * avoid locking AGs out of order the lowspace algorithm will start searching + * for free space from AG 0. If the correct transaction reservations have been + * made then this algorithm will eventually find all the space it needs. + */ +#define XFS_TRANS_LOWMODE 0x100 /* allocate in low space mode */ /* * Field values for xfs_trans_mod_sb. |