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authorBrian Foster <bfoster@redhat.com>2014-07-24 13:49:28 +0400
committerDave Chinner <david@fromorbit.com>2014-07-24 13:49:28 +0400
commitdc06f398f00059707236d456d954a3a9d2a829db (patch)
treeb7d0f9a2d9a109a32e6b72af3909b9465b406c23 /fs/xfs/xfs_dquot.h
parentf4526397928fff052f795713748f376a2bba1b5e (diff)
downloadlinux-dc06f398f00059707236d456d954a3a9d2a829db.tar.xz
xfs: run an eofblocks scan on ENOSPC/EDQUOT
From: Brian Foster <bfoster@redhat.com> Speculative preallocation and and the associated throttling metrics assume we're working with large files on large filesystems. Users have reported inefficiencies in these mechanisms when we happen to be dealing with large files on smaller filesystems. This can occur because while prealloc throttling is aggressive under low free space conditions, it is not active until we reach 5% free space or less. For example, a 40GB filesystem has enough space for several files large enough to have multi-GB preallocations at any given time. If those files are slow growing, they might reserve preallocation for long periods of time as well as avoid the background scanner due to frequent modification. If a new file is written under these conditions, said file has no access to this already reserved space and premature ENOSPC is imminent. To handle this scenario, modify the buffered write ENOSPC handling and retry sequence to invoke an eofblocks scan. In the smaller filesystem scenario, the eofblocks scan resets the usage of preallocation such that when the 5% free space threshold is met, throttling effectively takes over to provide fair and efficient preallocation until legitimate ENOSPC. The eofblocks scan is selective based on the nature of the failure. For example, an EDQUOT failure in a particular quota will use a filtered scan for that quota. Because we don't know which quota might have caused an allocation failure at any given time, we include each applicable quota determined to be under low free space conditions in the scan. Signed-off-by: Brian Foster <bfoster@redhat.com> Reviewed-by: Dave Chinner <dchinner@redhat.com> Signed-off-by: Dave Chinner <david@fromorbit.com>
Diffstat (limited to 'fs/xfs/xfs_dquot.h')
-rw-r--r--fs/xfs/xfs_dquot.h15
1 files changed, 15 insertions, 0 deletions
diff --git a/fs/xfs/xfs_dquot.h b/fs/xfs/xfs_dquot.h
index 68a68f704837..c24c67e22a2a 100644
--- a/fs/xfs/xfs_dquot.h
+++ b/fs/xfs/xfs_dquot.h
@@ -139,6 +139,21 @@ static inline xfs_dquot_t *xfs_inode_dquot(struct xfs_inode *ip, int type)
}
}
+/*
+ * Check whether a dquot is under low free space conditions. We assume the quota
+ * is enabled and enforced.
+ */
+static inline bool xfs_dquot_lowsp(struct xfs_dquot *dqp)
+{
+ int64_t freesp;
+
+ freesp = be64_to_cpu(dqp->q_core.d_blk_hardlimit) - dqp->q_res_bcount;
+ if (freesp < dqp->q_low_space[XFS_QLOWSP_1_PCNT])
+ return true;
+
+ return false;
+}
+
#define XFS_DQ_IS_LOCKED(dqp) (mutex_is_locked(&((dqp)->q_qlock)))
#define XFS_DQ_IS_DIRTY(dqp) ((dqp)->dq_flags & XFS_DQ_DIRTY)
#define XFS_QM_ISUDQ(dqp) ((dqp)->dq_flags & XFS_DQ_USER)