linux/fs/xfs/xfs_bmap_util.h
Dave Chinner 1f6d64829d xfs: block allocation work needs to be kswapd aware
Upon memory pressure, kswapd calls xfs_vm_writepage() from
shrink_page_list(). This can result in delayed allocation occurring
and that gets deferred to the the allocation workqueue.

The allocation then runs outside kswapd context, which means if it
needs memory (and it does to demand page metadata from disk) it can
block in shrink_inactive_list() waiting for IO congestion. These
blocking waits are normally avoiding in kswapd context, so under
memory pressure writeback from kswapd can be arbitrarily delayed by
memory reclaim.

To avoid this, pass the kswapd context to the allocation being done
by the workqueue, so that memory reclaim understands correctly that
the work is being done for kswapd and therefore it is not blocked
and does not delay memory reclaim.

To avoid issues with int->char conversion of flag fields (as noticed
in v1 of this patch) convert the flag fields in the struct
xfs_bmalloca to bool types. pahole indicates these variables are
still single byte variables, so no extra space is consumed by this
change.

cc: <stable@vger.kernel.org>
Reported-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Dave Chinner <david@fromorbit.com>
2014-06-06 15:59:59 +10:00

117 lines
4.4 KiB
C

/*
* Copyright (c) 2000-2006 Silicon Graphics, Inc.
* All Rights Reserved.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License as
* published by the Free Software Foundation.
*
* This program is distributed in the hope that it would be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*/
#ifndef __XFS_BMAP_UTIL_H__
#define __XFS_BMAP_UTIL_H__
/* Kernel only BMAP related definitions and functions */
struct xfs_bmbt_irec;
struct xfs_bmap_free_item;
struct xfs_ifork;
struct xfs_inode;
struct xfs_mount;
struct xfs_trans;
/*
* Argument structure for xfs_bmap_alloc.
*/
struct xfs_bmalloca {
xfs_fsblock_t *firstblock; /* i/o first block allocated */
struct xfs_bmap_free *flist; /* bmap freelist */
struct xfs_trans *tp; /* transaction pointer */
struct xfs_inode *ip; /* incore inode pointer */
struct xfs_bmbt_irec prev; /* extent before the new one */
struct xfs_bmbt_irec got; /* extent after, or delayed */
xfs_fileoff_t offset; /* offset in file filling in */
xfs_extlen_t length; /* i/o length asked/allocated */
xfs_fsblock_t blkno; /* starting block of new extent */
struct xfs_btree_cur *cur; /* btree cursor */
xfs_extnum_t idx; /* current extent index */
int nallocs;/* number of extents alloc'd */
int logflags;/* flags for transaction logging */
xfs_extlen_t total; /* total blocks needed for xaction */
xfs_extlen_t minlen; /* minimum allocation size (blocks) */
xfs_extlen_t minleft; /* amount must be left after alloc */
bool eof; /* set if allocating past last extent */
bool wasdel; /* replacing a delayed allocation */
bool userdata;/* set if is user data */
bool aeof; /* allocated space at eof */
bool conv; /* overwriting unwritten extents */
bool stack_switch;
bool kswapd; /* allocation in kswapd context */
int flags;
struct completion *done;
struct work_struct work;
int result;
};
int xfs_bmap_finish(struct xfs_trans **tp, struct xfs_bmap_free *flist,
int *committed);
int xfs_bmap_rtalloc(struct xfs_bmalloca *ap);
int xfs_bmapi_allocate(struct xfs_bmalloca *args);
int __xfs_bmapi_allocate(struct xfs_bmalloca *args);
int xfs_bmap_eof(struct xfs_inode *ip, xfs_fileoff_t endoff,
int whichfork, int *eof);
int xfs_bmap_count_blocks(struct xfs_trans *tp, struct xfs_inode *ip,
int whichfork, int *count);
int xfs_bmap_punch_delalloc_range(struct xfs_inode *ip,
xfs_fileoff_t start_fsb, xfs_fileoff_t length);
/* bmap to userspace formatter - copy to user & advance pointer */
typedef int (*xfs_bmap_format_t)(void **, struct getbmapx *, int *);
int xfs_getbmap(struct xfs_inode *ip, struct getbmapx *bmv,
xfs_bmap_format_t formatter, void *arg);
/* functions in xfs_bmap.c that are only needed by xfs_bmap_util.c */
void xfs_bmap_del_free(struct xfs_bmap_free *flist,
struct xfs_bmap_free_item *prev,
struct xfs_bmap_free_item *free);
int xfs_bmap_extsize_align(struct xfs_mount *mp, struct xfs_bmbt_irec *gotp,
struct xfs_bmbt_irec *prevp, xfs_extlen_t extsz,
int rt, int eof, int delay, int convert,
xfs_fileoff_t *offp, xfs_extlen_t *lenp);
void xfs_bmap_adjacent(struct xfs_bmalloca *ap);
int xfs_bmap_last_extent(struct xfs_trans *tp, struct xfs_inode *ip,
int whichfork, struct xfs_bmbt_irec *rec,
int *is_empty);
/* preallocation and hole punch interface */
int xfs_alloc_file_space(struct xfs_inode *ip, xfs_off_t offset,
xfs_off_t len, int alloc_type);
int xfs_free_file_space(struct xfs_inode *ip, xfs_off_t offset,
xfs_off_t len);
int xfs_zero_file_space(struct xfs_inode *ip, xfs_off_t offset,
xfs_off_t len);
int xfs_collapse_file_space(struct xfs_inode *, xfs_off_t offset,
xfs_off_t len);
/* EOF block manipulation functions */
bool xfs_can_free_eofblocks(struct xfs_inode *ip, bool force);
int xfs_free_eofblocks(struct xfs_mount *mp, struct xfs_inode *ip,
bool need_iolock);
int xfs_swap_extents(struct xfs_inode *ip, struct xfs_inode *tip,
struct xfs_swapext *sx);
xfs_daddr_t xfs_fsb_to_db(struct xfs_inode *ip, xfs_fsblock_t fsb);
#endif /* __XFS_BMAP_UTIL_H__ */