linux-stable/fs/xfs/xfs_fsops.c
Dave Chinner 41e6362183 xfs: xfs_do_force_shutdown needs to block racing shutdowns
When we call xfs_forced_shutdown(), the caller often expects the
filesystem to be completely shut down when it returns. However,
if we have racing xfs_forced_shutdown() calls, the first caller sets
the mount shutdown flag then goes to shutdown the log. The second
caller sees the mount shutdown flag and returns immediately - it
does not wait for the log to be shut down.

Unfortunately, xfs_forced_shutdown() is used in some places that
expect it to completely shut down the filesystem before it returns
(e.g. xfs_trans_log_inode()). As such, returning before the log has
been shut down leaves us in a place where the transaction failed to
complete correctly but we still call xfs_trans_commit(). This
situation arises because xfs_trans_log_inode() does not return an
error and instead calls xfs_force_shutdown() to ensure that the
transaction being committed is aborted.

Unfortunately, we have a race condition where xfs_trans_commit()
needs to check xlog_is_shutdown() because it can't abort log items
before the log is shut down, but it needs to use xfs_is_shutdown()
because xfs_forced_shutdown() does not block waiting for the log to
shut down.

To fix this conundrum, first we make all calls to
xfs_forced_shutdown() block until the log is also shut down. This
means we can then safely use xfs_forced_shutdown() as a mechanism
that ensures the currently running transaction will be aborted by
xfs_trans_commit() regardless of the shutdown check it uses.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
2022-03-29 18:22:01 -07:00

606 lines
15 KiB
C

// SPDX-License-Identifier: GPL-2.0
/*
* Copyright (c) 2000-2005 Silicon Graphics, Inc.
* All Rights Reserved.
*/
#include "xfs.h"
#include "xfs_fs.h"
#include "xfs_shared.h"
#include "xfs_format.h"
#include "xfs_log_format.h"
#include "xfs_trans_resv.h"
#include "xfs_sb.h"
#include "xfs_mount.h"
#include "xfs_trans.h"
#include "xfs_error.h"
#include "xfs_alloc.h"
#include "xfs_fsops.h"
#include "xfs_trans_space.h"
#include "xfs_log.h"
#include "xfs_log_priv.h"
#include "xfs_ag.h"
#include "xfs_ag_resv.h"
#include "xfs_trace.h"
/*
* Write new AG headers to disk. Non-transactional, but need to be
* written and completed prior to the growfs transaction being logged.
* To do this, we use a delayed write buffer list and wait for
* submission and IO completion of the list as a whole. This allows the
* IO subsystem to merge all the AG headers in a single AG into a single
* IO and hide most of the latency of the IO from us.
*
* This also means that if we get an error whilst building the buffer
* list to write, we can cancel the entire list without having written
* anything.
*/
static int
xfs_resizefs_init_new_ags(
struct xfs_trans *tp,
struct aghdr_init_data *id,
xfs_agnumber_t oagcount,
xfs_agnumber_t nagcount,
xfs_rfsblock_t delta,
bool *lastag_extended)
{
struct xfs_mount *mp = tp->t_mountp;
xfs_rfsblock_t nb = mp->m_sb.sb_dblocks + delta;
int error;
*lastag_extended = false;
INIT_LIST_HEAD(&id->buffer_list);
for (id->agno = nagcount - 1;
id->agno >= oagcount;
id->agno--, delta -= id->agsize) {
if (id->agno == nagcount - 1)
id->agsize = nb - (id->agno *
(xfs_rfsblock_t)mp->m_sb.sb_agblocks);
else
id->agsize = mp->m_sb.sb_agblocks;
error = xfs_ag_init_headers(mp, id);
if (error) {
xfs_buf_delwri_cancel(&id->buffer_list);
return error;
}
}
error = xfs_buf_delwri_submit(&id->buffer_list);
if (error)
return error;
if (delta) {
*lastag_extended = true;
error = xfs_ag_extend_space(mp, tp, id, delta);
}
return error;
}
/*
* growfs operations
*/
static int
xfs_growfs_data_private(
struct xfs_mount *mp, /* mount point for filesystem */
struct xfs_growfs_data *in) /* growfs data input struct */
{
struct xfs_buf *bp;
int error;
xfs_agnumber_t nagcount;
xfs_agnumber_t nagimax = 0;
xfs_rfsblock_t nb, nb_div, nb_mod;
int64_t delta;
bool lastag_extended;
xfs_agnumber_t oagcount;
struct xfs_trans *tp;
struct aghdr_init_data id = {};
nb = in->newblocks;
error = xfs_sb_validate_fsb_count(&mp->m_sb, nb);
if (error)
return error;
if (nb > mp->m_sb.sb_dblocks) {
error = xfs_buf_read_uncached(mp->m_ddev_targp,
XFS_FSB_TO_BB(mp, nb) - XFS_FSS_TO_BB(mp, 1),
XFS_FSS_TO_BB(mp, 1), 0, &bp, NULL);
if (error)
return error;
xfs_buf_relse(bp);
}
nb_div = nb;
nb_mod = do_div(nb_div, mp->m_sb.sb_agblocks);
nagcount = nb_div + (nb_mod != 0);
if (nb_mod && nb_mod < XFS_MIN_AG_BLOCKS) {
nagcount--;
nb = (xfs_rfsblock_t)nagcount * mp->m_sb.sb_agblocks;
}
delta = nb - mp->m_sb.sb_dblocks;
/*
* Reject filesystems with a single AG because they are not
* supported, and reject a shrink operation that would cause a
* filesystem to become unsupported.
*/
if (delta < 0 && nagcount < 2)
return -EINVAL;
oagcount = mp->m_sb.sb_agcount;
/* allocate the new per-ag structures */
if (nagcount > oagcount) {
error = xfs_initialize_perag(mp, nagcount, &nagimax);
if (error)
return error;
} else if (nagcount < oagcount) {
/* TODO: shrinking the entire AGs hasn't yet completed */
return -EINVAL;
}
error = xfs_trans_alloc(mp, &M_RES(mp)->tr_growdata,
(delta > 0 ? XFS_GROWFS_SPACE_RES(mp) : -delta), 0,
XFS_TRANS_RESERVE, &tp);
if (error)
return error;
if (delta > 0) {
error = xfs_resizefs_init_new_ags(tp, &id, oagcount, nagcount,
delta, &lastag_extended);
} else {
static struct ratelimit_state shrink_warning = \
RATELIMIT_STATE_INIT("shrink_warning", 86400 * HZ, 1);
ratelimit_set_flags(&shrink_warning, RATELIMIT_MSG_ON_RELEASE);
if (__ratelimit(&shrink_warning))
xfs_alert(mp,
"EXPERIMENTAL online shrink feature in use. Use at your own risk!");
error = xfs_ag_shrink_space(mp, &tp, nagcount - 1, -delta);
}
if (error)
goto out_trans_cancel;
/*
* Update changed superblock fields transactionally. These are not
* seen by the rest of the world until the transaction commit applies
* them atomically to the superblock.
*/
if (nagcount > oagcount)
xfs_trans_mod_sb(tp, XFS_TRANS_SB_AGCOUNT, nagcount - oagcount);
if (delta)
xfs_trans_mod_sb(tp, XFS_TRANS_SB_DBLOCKS, delta);
if (id.nfree)
xfs_trans_mod_sb(tp, XFS_TRANS_SB_FDBLOCKS, id.nfree);
/*
* Sync sb counters now to reflect the updated values. This is
* particularly important for shrink because the write verifier
* will fail if sb_fdblocks is ever larger than sb_dblocks.
*/
if (xfs_has_lazysbcount(mp))
xfs_log_sb(tp);
xfs_trans_set_sync(tp);
error = xfs_trans_commit(tp);
if (error)
return error;
/* New allocation groups fully initialized, so update mount struct */
if (nagimax)
mp->m_maxagi = nagimax;
xfs_set_low_space_thresholds(mp);
mp->m_alloc_set_aside = xfs_alloc_set_aside(mp);
if (delta > 0) {
/*
* If we expanded the last AG, free the per-AG reservation
* so we can reinitialize it with the new size.
*/
if (lastag_extended) {
struct xfs_perag *pag;
pag = xfs_perag_get(mp, id.agno);
error = xfs_ag_resv_free(pag);
xfs_perag_put(pag);
if (error)
return error;
}
/*
* Reserve AG metadata blocks. ENOSPC here does not mean there
* was a growfs failure, just that there still isn't space for
* new user data after the grow has been run.
*/
error = xfs_fs_reserve_ag_blocks(mp);
if (error == -ENOSPC)
error = 0;
}
return error;
out_trans_cancel:
xfs_trans_cancel(tp);
return error;
}
static int
xfs_growfs_log_private(
struct xfs_mount *mp, /* mount point for filesystem */
struct xfs_growfs_log *in) /* growfs log input struct */
{
xfs_extlen_t nb;
nb = in->newblocks;
if (nb < XFS_MIN_LOG_BLOCKS || nb < XFS_B_TO_FSB(mp, XFS_MIN_LOG_BYTES))
return -EINVAL;
if (nb == mp->m_sb.sb_logblocks &&
in->isint == (mp->m_sb.sb_logstart != 0))
return -EINVAL;
/*
* Moving the log is hard, need new interfaces to sync
* the log first, hold off all activity while moving it.
* Can have shorter or longer log in the same space,
* or transform internal to external log or vice versa.
*/
return -ENOSYS;
}
static int
xfs_growfs_imaxpct(
struct xfs_mount *mp,
__u32 imaxpct)
{
struct xfs_trans *tp;
int dpct;
int error;
if (imaxpct > 100)
return -EINVAL;
error = xfs_trans_alloc(mp, &M_RES(mp)->tr_growdata,
XFS_GROWFS_SPACE_RES(mp), 0, XFS_TRANS_RESERVE, &tp);
if (error)
return error;
dpct = imaxpct - mp->m_sb.sb_imax_pct;
xfs_trans_mod_sb(tp, XFS_TRANS_SB_IMAXPCT, dpct);
xfs_trans_set_sync(tp);
return xfs_trans_commit(tp);
}
/*
* protected versions of growfs function acquire and release locks on the mount
* point - exported through ioctls: XFS_IOC_FSGROWFSDATA, XFS_IOC_FSGROWFSLOG,
* XFS_IOC_FSGROWFSRT
*/
int
xfs_growfs_data(
struct xfs_mount *mp,
struct xfs_growfs_data *in)
{
int error = 0;
if (!capable(CAP_SYS_ADMIN))
return -EPERM;
if (!mutex_trylock(&mp->m_growlock))
return -EWOULDBLOCK;
/* update imaxpct separately to the physical grow of the filesystem */
if (in->imaxpct != mp->m_sb.sb_imax_pct) {
error = xfs_growfs_imaxpct(mp, in->imaxpct);
if (error)
goto out_error;
}
if (in->newblocks != mp->m_sb.sb_dblocks) {
error = xfs_growfs_data_private(mp, in);
if (error)
goto out_error;
}
/* Post growfs calculations needed to reflect new state in operations */
if (mp->m_sb.sb_imax_pct) {
uint64_t icount = mp->m_sb.sb_dblocks * mp->m_sb.sb_imax_pct;
do_div(icount, 100);
M_IGEO(mp)->maxicount = XFS_FSB_TO_INO(mp, icount);
} else
M_IGEO(mp)->maxicount = 0;
/* Update secondary superblocks now the physical grow has completed */
error = xfs_update_secondary_sbs(mp);
out_error:
/*
* Increment the generation unconditionally, the error could be from
* updating the secondary superblocks, in which case the new size
* is live already.
*/
mp->m_generation++;
mutex_unlock(&mp->m_growlock);
return error;
}
int
xfs_growfs_log(
xfs_mount_t *mp,
struct xfs_growfs_log *in)
{
int error;
if (!capable(CAP_SYS_ADMIN))
return -EPERM;
if (!mutex_trylock(&mp->m_growlock))
return -EWOULDBLOCK;
error = xfs_growfs_log_private(mp, in);
mutex_unlock(&mp->m_growlock);
return error;
}
/*
* exported through ioctl XFS_IOC_FSCOUNTS
*/
void
xfs_fs_counts(
xfs_mount_t *mp,
xfs_fsop_counts_t *cnt)
{
cnt->allocino = percpu_counter_read_positive(&mp->m_icount);
cnt->freeino = percpu_counter_read_positive(&mp->m_ifree);
cnt->freedata = percpu_counter_read_positive(&mp->m_fdblocks) -
xfs_fdblocks_unavailable(mp);
spin_lock(&mp->m_sb_lock);
cnt->freertx = mp->m_sb.sb_frextents;
spin_unlock(&mp->m_sb_lock);
}
/*
* exported through ioctl XFS_IOC_SET_RESBLKS & XFS_IOC_GET_RESBLKS
*
* xfs_reserve_blocks is called to set m_resblks
* in the in-core mount table. The number of unused reserved blocks
* is kept in m_resblks_avail.
*
* Reserve the requested number of blocks if available. Otherwise return
* as many as possible to satisfy the request. The actual number
* reserved are returned in outval
*
* A null inval pointer indicates that only the current reserved blocks
* available should be returned no settings are changed.
*/
int
xfs_reserve_blocks(
xfs_mount_t *mp,
uint64_t *inval,
xfs_fsop_resblks_t *outval)
{
int64_t lcounter, delta;
int64_t fdblks_delta = 0;
uint64_t request;
int64_t free;
int error = 0;
/* If inval is null, report current values and return */
if (inval == (uint64_t *)NULL) {
if (!outval)
return -EINVAL;
outval->resblks = mp->m_resblks;
outval->resblks_avail = mp->m_resblks_avail;
return 0;
}
request = *inval;
/*
* With per-cpu counters, this becomes an interesting problem. we need
* to work out if we are freeing or allocation blocks first, then we can
* do the modification as necessary.
*
* We do this under the m_sb_lock so that if we are near ENOSPC, we will
* hold out any changes while we work out what to do. This means that
* the amount of free space can change while we do this, so we need to
* retry if we end up trying to reserve more space than is available.
*/
spin_lock(&mp->m_sb_lock);
/*
* If our previous reservation was larger than the current value,
* then move any unused blocks back to the free pool. Modify the resblks
* counters directly since we shouldn't have any problems unreserving
* space.
*/
if (mp->m_resblks > request) {
lcounter = mp->m_resblks_avail - request;
if (lcounter > 0) { /* release unused blocks */
fdblks_delta = lcounter;
mp->m_resblks_avail -= lcounter;
}
mp->m_resblks = request;
if (fdblks_delta) {
spin_unlock(&mp->m_sb_lock);
error = xfs_mod_fdblocks(mp, fdblks_delta, 0);
spin_lock(&mp->m_sb_lock);
}
goto out;
}
/*
* If the request is larger than the current reservation, reserve the
* blocks before we update the reserve counters. Sample m_fdblocks and
* perform a partial reservation if the request exceeds free space.
*
* The code below estimates how many blocks it can request from
* fdblocks to stash in the reserve pool. This is a classic TOCTOU
* race since fdblocks updates are not always coordinated via
* m_sb_lock. Set the reserve size even if there's not enough free
* space to fill it because mod_fdblocks will refill an undersized
* reserve when it can.
*/
free = percpu_counter_sum(&mp->m_fdblocks) -
xfs_fdblocks_unavailable(mp);
delta = request - mp->m_resblks;
mp->m_resblks = request;
if (delta > 0 && free > 0) {
/*
* We'll either succeed in getting space from the free block
* count or we'll get an ENOSPC. Don't set the reserved flag
* here - we don't want to reserve the extra reserve blocks
* from the reserve.
*
* The desired reserve size can change after we drop the lock.
* Use mod_fdblocks to put the space into the reserve or into
* fdblocks as appropriate.
*/
fdblks_delta = min(free, delta);
spin_unlock(&mp->m_sb_lock);
error = xfs_mod_fdblocks(mp, -fdblks_delta, 0);
if (!error)
xfs_mod_fdblocks(mp, fdblks_delta, 0);
spin_lock(&mp->m_sb_lock);
}
out:
if (outval) {
outval->resblks = mp->m_resblks;
outval->resblks_avail = mp->m_resblks_avail;
}
spin_unlock(&mp->m_sb_lock);
return error;
}
int
xfs_fs_goingdown(
xfs_mount_t *mp,
uint32_t inflags)
{
switch (inflags) {
case XFS_FSOP_GOING_FLAGS_DEFAULT: {
if (!freeze_bdev(mp->m_super->s_bdev)) {
xfs_force_shutdown(mp, SHUTDOWN_FORCE_UMOUNT);
thaw_bdev(mp->m_super->s_bdev);
}
break;
}
case XFS_FSOP_GOING_FLAGS_LOGFLUSH:
xfs_force_shutdown(mp, SHUTDOWN_FORCE_UMOUNT);
break;
case XFS_FSOP_GOING_FLAGS_NOLOGFLUSH:
xfs_force_shutdown(mp,
SHUTDOWN_FORCE_UMOUNT | SHUTDOWN_LOG_IO_ERROR);
break;
default:
return -EINVAL;
}
return 0;
}
/*
* Force a shutdown of the filesystem instantly while keeping the filesystem
* consistent. We don't do an unmount here; just shutdown the shop, make sure
* that absolutely nothing persistent happens to this filesystem after this
* point.
*
* The shutdown state change is atomic, resulting in the first and only the
* first shutdown call processing the shutdown. This means we only shutdown the
* log once as it requires, and we don't spam the logs when multiple concurrent
* shutdowns race to set the shutdown flags.
*/
void
xfs_do_force_shutdown(
struct xfs_mount *mp,
int flags,
char *fname,
int lnnum)
{
int tag;
const char *why;
if (test_and_set_bit(XFS_OPSTATE_SHUTDOWN, &mp->m_opstate)) {
xlog_shutdown_wait(mp->m_log);
return;
}
if (mp->m_sb_bp)
mp->m_sb_bp->b_flags |= XBF_DONE;
if (flags & SHUTDOWN_FORCE_UMOUNT)
xfs_alert(mp, "User initiated shutdown received.");
if (xlog_force_shutdown(mp->m_log, flags)) {
tag = XFS_PTAG_SHUTDOWN_LOGERROR;
why = "Log I/O Error";
} else if (flags & SHUTDOWN_CORRUPT_INCORE) {
tag = XFS_PTAG_SHUTDOWN_CORRUPT;
why = "Corruption of in-memory data";
} else {
tag = XFS_PTAG_SHUTDOWN_IOERROR;
why = "Metadata I/O Error";
}
trace_xfs_force_shutdown(mp, tag, flags, fname, lnnum);
xfs_alert_tag(mp, tag,
"%s (0x%x) detected at %pS (%s:%d). Shutting down filesystem.",
why, flags, __return_address, fname, lnnum);
xfs_alert(mp,
"Please unmount the filesystem and rectify the problem(s)");
if (xfs_error_level >= XFS_ERRLEVEL_HIGH)
xfs_stack_trace();
}
/*
* Reserve free space for per-AG metadata.
*/
int
xfs_fs_reserve_ag_blocks(
struct xfs_mount *mp)
{
xfs_agnumber_t agno;
struct xfs_perag *pag;
int error = 0;
int err2;
mp->m_finobt_nores = false;
for_each_perag(mp, agno, pag) {
err2 = xfs_ag_resv_init(pag, NULL);
if (err2 && !error)
error = err2;
}
if (error && error != -ENOSPC) {
xfs_warn(mp,
"Error %d reserving per-AG metadata reserve pool.", error);
xfs_force_shutdown(mp, SHUTDOWN_CORRUPT_INCORE);
}
return error;
}
/*
* Free space reserved for per-AG metadata.
*/
int
xfs_fs_unreserve_ag_blocks(
struct xfs_mount *mp)
{
xfs_agnumber_t agno;
struct xfs_perag *pag;
int error = 0;
int err2;
for_each_perag(mp, agno, pag) {
err2 = xfs_ag_resv_free(pag);
if (err2 && !error)
error = err2;
}
if (error)
xfs_warn(mp,
"Error %d freeing per-AG metadata reserve pool.", error);
return error;
}