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![Brian Foster](/assets/img/avatar_default.png)
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>
188 lines
5.5 KiB
C
188 lines
5.5 KiB
C
/*
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* Copyright (c) 2000-2005 Silicon Graphics, Inc.
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* All Rights Reserved.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License as
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* published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it would be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write the Free Software Foundation,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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#ifndef __XFS_DQUOT_H__
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#define __XFS_DQUOT_H__
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/*
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* Dquots are structures that hold quota information about a user or a group,
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* much like inodes are for files. In fact, dquots share many characteristics
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* with inodes. However, dquots can also be a centralized resource, relative
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* to a collection of inodes. In this respect, dquots share some characteristics
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* of the superblock.
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* XFS dquots exploit both those in its algorithms. They make every attempt
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* to not be a bottleneck when quotas are on and have minimal impact, if any,
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* when quotas are off.
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*/
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struct xfs_mount;
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struct xfs_trans;
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enum {
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XFS_QLOWSP_1_PCNT = 0,
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XFS_QLOWSP_3_PCNT,
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XFS_QLOWSP_5_PCNT,
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XFS_QLOWSP_MAX
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};
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/*
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* The incore dquot structure
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*/
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typedef struct xfs_dquot {
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uint dq_flags; /* various flags (XFS_DQ_*) */
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struct list_head q_lru; /* global free list of dquots */
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struct xfs_mount*q_mount; /* filesystem this relates to */
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struct xfs_trans*q_transp; /* trans this belongs to currently */
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uint q_nrefs; /* # active refs from inodes */
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xfs_daddr_t q_blkno; /* blkno of dquot buffer */
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int q_bufoffset; /* off of dq in buffer (# dquots) */
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xfs_fileoff_t q_fileoffset; /* offset in quotas file */
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xfs_disk_dquot_t q_core; /* actual usage & quotas */
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xfs_dq_logitem_t q_logitem; /* dquot log item */
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xfs_qcnt_t q_res_bcount; /* total regular nblks used+reserved */
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xfs_qcnt_t q_res_icount; /* total inos allocd+reserved */
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xfs_qcnt_t q_res_rtbcount;/* total realtime blks used+reserved */
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xfs_qcnt_t q_prealloc_lo_wmark;/* prealloc throttle wmark */
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xfs_qcnt_t q_prealloc_hi_wmark;/* prealloc disabled wmark */
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int64_t q_low_space[XFS_QLOWSP_MAX];
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struct mutex q_qlock; /* quota lock */
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struct completion q_flush; /* flush completion queue */
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atomic_t q_pincount; /* dquot pin count */
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wait_queue_head_t q_pinwait; /* dquot pinning wait queue */
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} xfs_dquot_t;
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/*
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* Lock hierarchy for q_qlock:
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* XFS_QLOCK_NORMAL is the implicit default,
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* XFS_QLOCK_NESTED is the dquot with the higher id in xfs_dqlock2
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*/
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enum {
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XFS_QLOCK_NORMAL = 0,
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XFS_QLOCK_NESTED,
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};
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/*
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* Manage the q_flush completion queue embedded in the dquot. This completion
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* queue synchronizes processes attempting to flush the in-core dquot back to
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* disk.
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*/
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static inline void xfs_dqflock(xfs_dquot_t *dqp)
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{
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wait_for_completion(&dqp->q_flush);
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}
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static inline int xfs_dqflock_nowait(xfs_dquot_t *dqp)
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{
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return try_wait_for_completion(&dqp->q_flush);
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}
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static inline void xfs_dqfunlock(xfs_dquot_t *dqp)
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{
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complete(&dqp->q_flush);
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}
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static inline int xfs_dqlock_nowait(struct xfs_dquot *dqp)
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{
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return mutex_trylock(&dqp->q_qlock);
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}
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static inline void xfs_dqlock(struct xfs_dquot *dqp)
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{
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mutex_lock(&dqp->q_qlock);
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}
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static inline void xfs_dqunlock(struct xfs_dquot *dqp)
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{
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mutex_unlock(&dqp->q_qlock);
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}
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static inline int xfs_this_quota_on(struct xfs_mount *mp, int type)
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{
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switch (type & XFS_DQ_ALLTYPES) {
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case XFS_DQ_USER:
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return XFS_IS_UQUOTA_ON(mp);
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case XFS_DQ_GROUP:
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return XFS_IS_GQUOTA_ON(mp);
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case XFS_DQ_PROJ:
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return XFS_IS_PQUOTA_ON(mp);
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default:
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return 0;
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}
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}
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static inline xfs_dquot_t *xfs_inode_dquot(struct xfs_inode *ip, int type)
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{
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switch (type & XFS_DQ_ALLTYPES) {
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case XFS_DQ_USER:
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return ip->i_udquot;
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case XFS_DQ_GROUP:
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return ip->i_gdquot;
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case XFS_DQ_PROJ:
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return ip->i_pdquot;
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default:
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return NULL;
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}
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}
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/*
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* Check whether a dquot is under low free space conditions. We assume the quota
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* is enabled and enforced.
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*/
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static inline bool xfs_dquot_lowsp(struct xfs_dquot *dqp)
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{
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int64_t freesp;
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freesp = be64_to_cpu(dqp->q_core.d_blk_hardlimit) - dqp->q_res_bcount;
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if (freesp < dqp->q_low_space[XFS_QLOWSP_1_PCNT])
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return true;
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return false;
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}
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#define XFS_DQ_IS_LOCKED(dqp) (mutex_is_locked(&((dqp)->q_qlock)))
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#define XFS_DQ_IS_DIRTY(dqp) ((dqp)->dq_flags & XFS_DQ_DIRTY)
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#define XFS_QM_ISUDQ(dqp) ((dqp)->dq_flags & XFS_DQ_USER)
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#define XFS_QM_ISPDQ(dqp) ((dqp)->dq_flags & XFS_DQ_PROJ)
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#define XFS_QM_ISGDQ(dqp) ((dqp)->dq_flags & XFS_DQ_GROUP)
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extern int xfs_qm_dqread(struct xfs_mount *, xfs_dqid_t, uint,
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uint, struct xfs_dquot **);
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extern void xfs_qm_dqdestroy(xfs_dquot_t *);
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extern int xfs_qm_dqflush(struct xfs_dquot *, struct xfs_buf **);
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extern void xfs_qm_dqunpin_wait(xfs_dquot_t *);
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extern void xfs_qm_adjust_dqtimers(xfs_mount_t *,
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xfs_disk_dquot_t *);
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extern void xfs_qm_adjust_dqlimits(struct xfs_mount *,
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struct xfs_dquot *);
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extern int xfs_qm_dqget(xfs_mount_t *, xfs_inode_t *,
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xfs_dqid_t, uint, uint, xfs_dquot_t **);
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extern void xfs_qm_dqput(xfs_dquot_t *);
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extern void xfs_dqlock2(struct xfs_dquot *, struct xfs_dquot *);
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extern void xfs_dquot_set_prealloc_limits(struct xfs_dquot *);
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static inline struct xfs_dquot *xfs_qm_dqhold(struct xfs_dquot *dqp)
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{
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xfs_dqlock(dqp);
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dqp->q_nrefs++;
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xfs_dqunlock(dqp);
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return dqp;
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}
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#endif /* __XFS_DQUOT_H__ */
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