linux/fs/xfs/xfs_rtalloc.h

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// SPDX-License-Identifier: GPL-2.0
/*
* Copyright (c) 2000-2003,2005 Silicon Graphics, Inc.
* All Rights Reserved.
*/
#ifndef __XFS_RTALLOC_H__
#define __XFS_RTALLOC_H__
/* kernel only definitions and functions */
struct xfs_mount;
struct xfs_trans;
#ifdef CONFIG_XFS_RT
/*
* Function prototypes for exported functions.
*/
/*
* Allocate an extent in the realtime subvolume, with the usual allocation
* parameters. The length units are all in realtime extents, as is the
* result block number.
*/
int /* error */
xfs_rtallocate_extent(
struct xfs_trans *tp, /* transaction pointer */
xfs_rtxnum_t start, /* starting rtext number to allocate */
xfs_rtxlen_t minlen, /* minimum length to allocate */
xfs_rtxlen_t maxlen, /* maximum length to allocate */
xfs_rtxlen_t *len, /* out: actual length allocated */
int wasdel, /* was a delayed allocation extent */
xfs_rtxlen_t prod, /* extent product factor */
xfs_rtxnum_t *rtblock); /* out: start rtext allocated */
/*
* Initialize realtime fields in the mount structure.
*/
int /* error */
xfs_rtmount_init(
struct xfs_mount *mp); /* file system mount structure */
void
xfs_rtunmount_inodes(
struct xfs_mount *mp);
/*
* Get the bitmap and summary inodes into the mount structure
* at mount time.
*/
int /* error */
xfs_rtmount_inodes(
struct xfs_mount *mp); /* file system mount structure */
/*
* Pick an extent for allocation at the start of a new realtime file.
* Use the sequence number stored in the atime field of the bitmap inode.
* Translate this to a fraction of the rtextents, and return the product
* of rtextents and the fraction.
* The fraction sequence is 0, 1/2, 1/4, 3/4, 1/8, ..., 7/8, 1/16, ...
*/
int /* error */
xfs_rtpick_extent(
struct xfs_mount *mp, /* file system mount point */
struct xfs_trans *tp, /* transaction pointer */
xfs_rtxlen_t len, /* allocation length (rtextents) */
xfs_rtxnum_t *pick); /* result rt extent */
/*
* Grow the realtime area of the filesystem.
*/
int
xfs_growfs_rt(
struct xfs_mount *mp, /* file system mount structure */
xfs_growfs_rt_t *in); /* user supplied growfs struct */
xfs: recalculate free rt extents after log recovery I've been observing periodic corruption reports from xfs_scrub involving the free rt extent counter (frextents) while running xfs/141. That test uses an error injection knob to induce a torn write to the log, and an arbitrary number of recovery mounts, frextents will count fewer free rt extents than can be found the rtbitmap. The root cause of the problem is a combination of the misuse of sb_frextents in the incore mount to reflect both incore reservations made by running transactions as well as the actual count of free rt extents on disk. The following sequence can reproduce the undercount: Thread 1 Thread 2 xfs_trans_alloc(rtextents=3) xfs_mod_frextents(-3) <blocks> xfs_attr_set() xfs_bmap_attr_addfork() xfs_add_attr2() xfs_log_sb() xfs_sb_to_disk() xfs_trans_commit() <log flushed to disk> <log goes down> Note that thread 1 subtracts 3 from sb_frextents even though it never commits to using that space. Thread 2 writes the undercounted value to the ondisk superblock and logs it to the xattr transaction, which is then flushed to disk. At next mount, log recovery will find the logged superblock and write that back into the filesystem. At the end of log recovery, we reread the superblock and install the recovered undercounted frextents value into the incore superblock. From that point on, we've effectively leaked thread 1's transaction reservation. The correct fix for this is to separate the incore reservation from the ondisk usage, but that's a matter for the next patch. Because the kernel has been logging superblocks with undercounted frextents for a very long time and we don't demand that sysadmins run xfs_repair after a crash, fix the undercount by recomputing frextents after log recovery. Gating this on log recovery is a reasonable balance (I think) between correcting the problem and slowing down every mount attempt. Note that xfs_repair will fix undercounted frextents. Signed-off-by: Darrick J. Wong <djwong@kernel.org> Reviewed-by: Dave Chinner <dchinner@redhat.com> Signed-off-by: Dave Chinner <david@fromorbit.com>
2022-04-11 20:49:42 +00:00
int xfs_rtalloc_reinit_frextents(struct xfs_mount *mp);
#else
# define xfs_rtallocate_extent(t,b,min,max,l,f,p,rb) (-ENOSYS)
# define xfs_rtpick_extent(m,t,l,rb) (-ENOSYS)
# define xfs_growfs_rt(mp,in) (-ENOSYS)
# define xfs_rtalloc_reinit_frextents(m) (0)
static inline int /* error */
xfs_rtmount_init(
xfs_mount_t *mp) /* file system mount structure */
{
if (mp->m_sb.sb_rblocks == 0)
return 0;
xfs_warn(mp, "Not built with CONFIG_XFS_RT");
return -ENOSYS;
}
# define xfs_rtmount_inodes(m) (((mp)->m_sb.sb_rblocks == 0)? 0 : (-ENOSYS))
# define xfs_rtunmount_inodes(m)
#endif /* CONFIG_XFS_RT */
#endif /* __XFS_RTALLOC_H__ */