From dc06f398f00059707236d456d954a3a9d2a829db Mon Sep 17 00:00:00 2001 From: Brian Foster Date: Thu, 24 Jul 2014 19:49:28 +1000 Subject: [PATCH] xfs: run an eofblocks scan on ENOSPC/EDQUOT From: Brian Foster 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 Reviewed-by: Dave Chinner Signed-off-by: Dave Chinner --- fs/xfs/xfs_dquot.h | 15 +++++++++++++ fs/xfs/xfs_file.c | 23 ++++++++++++++++---- fs/xfs/xfs_icache.c | 52 +++++++++++++++++++++++++++++++++++++++++++++ fs/xfs/xfs_icache.h | 1 + 4 files changed, 87 insertions(+), 4 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) diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c index 181605da08e4..fcf91a22f5d8 100644 --- a/fs/xfs/xfs_file.c +++ b/fs/xfs/xfs_file.c @@ -38,6 +38,7 @@ #include "xfs_trace.h" #include "xfs_log.h" #include "xfs_dinode.h" +#include "xfs_icache.h" #include #include @@ -689,14 +690,28 @@ write_retry: ret = generic_perform_write(file, from, pos); if (likely(ret >= 0)) iocb->ki_pos = pos + ret; + /* - * If we just got an ENOSPC, try to write back all dirty inodes to - * convert delalloc space to free up some of the excess reserved - * metadata space. + * If we hit a space limit, try to free up some lingering preallocated + * space before returning an error. In the case of ENOSPC, first try to + * write back all dirty inodes to free up some of the excess reserved + * metadata space. This reduces the chances that the eofblocks scan + * waits on dirty mappings. Since xfs_flush_inodes() is serialized, this + * also behaves as a filter to prevent too many eofblocks scans from + * running at the same time. */ - if (ret == -ENOSPC && !enospc) { + if (ret == -EDQUOT && !enospc) { + enospc = xfs_inode_free_quota_eofblocks(ip); + if (enospc) + goto write_retry; + } else if (ret == -ENOSPC && !enospc) { + struct xfs_eofblocks eofb = {0}; + enospc = 1; xfs_flush_inodes(ip->i_mount); + eofb.eof_scan_owner = ip->i_ino; /* for locking */ + eofb.eof_flags = XFS_EOF_FLAGS_SYNC; + xfs_icache_free_eofblocks(ip->i_mount, &eofb); goto write_retry; } diff --git a/fs/xfs/xfs_icache.c b/fs/xfs/xfs_icache.c index 43452081b705..981b2cf51985 100644 --- a/fs/xfs/xfs_icache.c +++ b/fs/xfs/xfs_icache.c @@ -33,6 +33,9 @@ #include "xfs_trace.h" #include "xfs_icache.h" #include "xfs_bmap_util.h" +#include "xfs_quota.h" +#include "xfs_dquot_item.h" +#include "xfs_dquot.h" #include #include @@ -1300,6 +1303,55 @@ xfs_icache_free_eofblocks( eofb, XFS_ICI_EOFBLOCKS_TAG); } +/* + * Run eofblocks scans on the quotas applicable to the inode. For inodes with + * multiple quotas, we don't know exactly which quota caused an allocation + * failure. We make a best effort by including each quota under low free space + * conditions (less than 1% free space) in the scan. + */ +int +xfs_inode_free_quota_eofblocks( + struct xfs_inode *ip) +{ + int scan = 0; + struct xfs_eofblocks eofb = {0}; + struct xfs_dquot *dq; + + ASSERT(xfs_isilocked(ip, XFS_IOLOCK_EXCL)); + + /* + * Set the scan owner to avoid a potential livelock. Otherwise, the scan + * can repeatedly trylock on the inode we're currently processing. We + * run a sync scan to increase effectiveness and use the union filter to + * cover all applicable quotas in a single scan. + */ + eofb.eof_scan_owner = ip->i_ino; + eofb.eof_flags = XFS_EOF_FLAGS_UNION|XFS_EOF_FLAGS_SYNC; + + if (XFS_IS_UQUOTA_ENFORCED(ip->i_mount)) { + dq = xfs_inode_dquot(ip, XFS_DQ_USER); + if (dq && xfs_dquot_lowsp(dq)) { + eofb.eof_uid = VFS_I(ip)->i_uid; + eofb.eof_flags |= XFS_EOF_FLAGS_UID; + scan = 1; + } + } + + if (XFS_IS_GQUOTA_ENFORCED(ip->i_mount)) { + dq = xfs_inode_dquot(ip, XFS_DQ_GROUP); + if (dq && xfs_dquot_lowsp(dq)) { + eofb.eof_gid = VFS_I(ip)->i_gid; + eofb.eof_flags |= XFS_EOF_FLAGS_GID; + scan = 1; + } + } + + if (scan) + xfs_icache_free_eofblocks(ip->i_mount, &eofb); + + return scan; +} + void xfs_inode_set_eofblocks_tag( xfs_inode_t *ip) diff --git a/fs/xfs/xfs_icache.h b/fs/xfs/xfs_icache.h index 98687af6a99d..46748b86b12f 100644 --- a/fs/xfs/xfs_icache.h +++ b/fs/xfs/xfs_icache.h @@ -58,6 +58,7 @@ void xfs_inode_set_reclaim_tag(struct xfs_inode *ip); void xfs_inode_set_eofblocks_tag(struct xfs_inode *ip); void xfs_inode_clear_eofblocks_tag(struct xfs_inode *ip); int xfs_icache_free_eofblocks(struct xfs_mount *, struct xfs_eofblocks *); +int xfs_inode_free_quota_eofblocks(struct xfs_inode *ip); void xfs_eofblocks_worker(struct work_struct *); int xfs_inode_ag_iterator(struct xfs_mount *mp, -- 2.39.5