diff options
| author | Brian Foster <bfoster@redhat.com> | 2018-08-01 07:20:31 -0700 |
|---|---|---|
| committer | Darrick J. Wong <darrick.wong@oracle.com> | 2018-08-02 23:05:13 -0700 |
| commit | 1214f1cf663b0939fbb8f1bccdc74c1d1e452d53 (patch) | |
| tree | 24a8b208cbfff610e5099eab6cdae0f474aad9df /fs/xfs/libxfs/xfs_shared.h | |
| parent | ce356d64772f920f26cd6c1b02878a737a275638 (diff) | |
xfs: replace dop_low with transaction flag
The dop_low field enables the low free space allocation mode when a
previous allocation has detected difficulty allocating blocks. It
has historically been part of the xfs_defer_ops structure, which
means if enabled, it remains enabled across a set of transactions
until the deferred operations have completed and the dfops is reset.
Now that the dfops is embedded in the transaction, we can save a bit
more space by using a transaction flag rather than a standalone
boolean. Drop the ->dop_low field and replace it with a transaction
flag that is set at the same points, carried across rolling
transactions and cleared on completion of deferred operations. This
essentially emulates the behavior of ->dop_low and so should not
change behavior.
Signed-off-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
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. |