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linux/fs/xfs/libxfs/xfs_dquot_buf.c
Dave Chinner 7d6a13f023 xfs: handle dquot buffer readahead in log recovery correctly 
When we do dquot readahead in log recovery, we do not use a verifier
as the underlying buffer may not have dquots in it. e.g. the
allocation operation hasn't yet been replayed. Hence we do not want
to fail recovery because we detect an operation to be replayed has
not been run yet. This problem was addressed for inodes in commit
d891400 ("xfs: inode buffers may not be valid during recovery
readahead") but the problem was not recognised to exist for dquots
and their buffers as the dquot readahead did not have a verifier.

The result of not using a verifier is that when the buffer is then
next read to replay a dquot modification, the dquot buffer verifier
will only be attached to the buffer if *readahead is not complete*.
Hence we can read the buffer, replay the dquot changes and then add
it to the delwri submission list without it having a verifier
attached to it. This then generates warnings in xfs_buf_ioapply(),
which catches and warns about this case.

Fix this and make it handle the same readahead verifier error cases
as for inode buffers by adding a new readahead verifier that has a
write operation as well as a read operation that marks the buffer as
not done if any corruption is detected.  Also make sure we don't run
readahead if the dquot buffer has been marked as cancelled by
recovery.

This will result in readahead either succeeding and the buffer
having a valid write verifier, or readahead failing and the buffer
state requiring the subsequent read to resubmit the IO with the new
verifier.  In either case, this will result in the buffer always
ending up with a valid write verifier on it.

Note: we also need to fix the inode buffer readahead error handling
to mark the buffer with EIO. Brian noticed the code I copied from
there wrong during review, so fix it at the same time. Add comments
linking the two functions that handle readahead verifier errors
together so we don't forget this behavioural link in future.

cc: <stable@vger.kernel.org> # 3.12 - current
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>
2016-01-12 07:04:01 +11:00

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/*
* Copyright (c) 2000-2006 Silicon Graphics, Inc.
* Copyright (c) 2013 Red Hat, 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
*/
#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_mount.h"
#include "xfs_inode.h"
#include "xfs_quota.h"
#include "xfs_trans.h"
#include "xfs_qm.h"
#include "xfs_error.h"
#include "xfs_cksum.h"
#include "xfs_trace.h"
int
xfs_calc_dquots_per_chunk(
unsigned int nbblks) /* basic block units */
{
unsigned int ndquots;
ASSERT(nbblks > 0);
ndquots = BBTOB(nbblks);
do_div(ndquots, sizeof(xfs_dqblk_t));
return ndquots;
}
/*
* Do some primitive error checking on ondisk dquot data structures.
*/
int
xfs_dqcheck(
struct xfs_mount *mp,
xfs_disk_dquot_t *ddq,
xfs_dqid_t id,
uint type, /* used only when IO_dorepair is true */
uint flags,
const char *str)
{
xfs_dqblk_t *d = (xfs_dqblk_t *)ddq;
int errs = 0;
/*
* We can encounter an uninitialized dquot buffer for 2 reasons:
* 1. If we crash while deleting the quotainode(s), and those blks got
* used for user data. This is because we take the path of regular
* file deletion; however, the size field of quotainodes is never
* updated, so all the tricks that we play in itruncate_finish
* don't quite matter.
*
* 2. We don't play the quota buffers when there's a quotaoff logitem.
* But the allocation will be replayed so we'll end up with an
* uninitialized quota block.
*
* This is all fine; things are still consistent, and we haven't lost
* any quota information. Just don't complain about bad dquot blks.
*/
if (ddq->d_magic != cpu_to_be16(XFS_DQUOT_MAGIC)) {
if (flags & XFS_QMOPT_DOWARN)
xfs_alert(mp,
"%s : XFS dquot ID 0x%x, magic 0x%x != 0x%x",
str, id, be16_to_cpu(ddq->d_magic), XFS_DQUOT_MAGIC);
errs++;
}
if (ddq->d_version != XFS_DQUOT_VERSION) {
if (flags & XFS_QMOPT_DOWARN)
xfs_alert(mp,
"%s : XFS dquot ID 0x%x, version 0x%x != 0x%x",
str, id, ddq->d_version, XFS_DQUOT_VERSION);
errs++;
}
if (ddq->d_flags != XFS_DQ_USER &&
ddq->d_flags != XFS_DQ_PROJ &&
ddq->d_flags != XFS_DQ_GROUP) {
if (flags & XFS_QMOPT_DOWARN)
xfs_alert(mp,
"%s : XFS dquot ID 0x%x, unknown flags 0x%x",
str, id, ddq->d_flags);
errs++;
}
if (id != -1 && id != be32_to_cpu(ddq->d_id)) {
if (flags & XFS_QMOPT_DOWARN)
xfs_alert(mp,
"%s : ondisk-dquot 0x%p, ID mismatch: "
"0x%x expected, found id 0x%x",
str, ddq, id, be32_to_cpu(ddq->d_id));
errs++;
}
if (!errs && ddq->d_id) {
if (ddq->d_blk_softlimit &&
be64_to_cpu(ddq->d_bcount) >
be64_to_cpu(ddq->d_blk_softlimit)) {
if (!ddq->d_btimer) {
if (flags & XFS_QMOPT_DOWARN)
xfs_alert(mp,
"%s : Dquot ID 0x%x (0x%p) BLK TIMER NOT STARTED",
str, (int)be32_to_cpu(ddq->d_id), ddq);
errs++;
}
}
if (ddq->d_ino_softlimit &&
be64_to_cpu(ddq->d_icount) >
be64_to_cpu(ddq->d_ino_softlimit)) {
if (!ddq->d_itimer) {
if (flags & XFS_QMOPT_DOWARN)
xfs_alert(mp,
"%s : Dquot ID 0x%x (0x%p) INODE TIMER NOT STARTED",
str, (int)be32_to_cpu(ddq->d_id), ddq);
errs++;
}
}
if (ddq->d_rtb_softlimit &&
be64_to_cpu(ddq->d_rtbcount) >
be64_to_cpu(ddq->d_rtb_softlimit)) {
if (!ddq->d_rtbtimer) {
if (flags & XFS_QMOPT_DOWARN)
xfs_alert(mp,
"%s : Dquot ID 0x%x (0x%p) RTBLK TIMER NOT STARTED",
str, (int)be32_to_cpu(ddq->d_id), ddq);
errs++;
}
}
}
if (!errs || !(flags & XFS_QMOPT_DQREPAIR))
return errs;
if (flags & XFS_QMOPT_DOWARN)
xfs_notice(mp, "Re-initializing dquot ID 0x%x", id);
/*
* Typically, a repair is only requested by quotacheck.
*/
ASSERT(id != -1);
ASSERT(flags & XFS_QMOPT_DQREPAIR);
memset(d, 0, sizeof(xfs_dqblk_t));
d->dd_diskdq.d_magic = cpu_to_be16(XFS_DQUOT_MAGIC);
d->dd_diskdq.d_version = XFS_DQUOT_VERSION;
d->dd_diskdq.d_flags = type;
d->dd_diskdq.d_id = cpu_to_be32(id);
if (xfs_sb_version_hascrc(&mp->m_sb)) {
uuid_copy(&d->dd_uuid, &mp->m_sb.sb_meta_uuid);
xfs_update_cksum((char *)d, sizeof(struct xfs_dqblk),
XFS_DQUOT_CRC_OFF);
}
return errs;
}
STATIC bool
xfs_dquot_buf_verify_crc(
struct xfs_mount *mp,
struct xfs_buf *bp)
{
struct xfs_dqblk *d = (struct xfs_dqblk *)bp->b_addr;
int ndquots;
int i;
if (!xfs_sb_version_hascrc(&mp->m_sb))
return true;
/*
* if we are in log recovery, the quota subsystem has not been
* initialised so we have no quotainfo structure. In that case, we need
* to manually calculate the number of dquots in the buffer.
*/
if (mp->m_quotainfo)
ndquots = mp->m_quotainfo->qi_dqperchunk;
else
ndquots = xfs_calc_dquots_per_chunk(
XFS_BB_TO_FSB(mp, bp->b_length));
for (i = 0; i < ndquots; i++, d++) {
if (!xfs_verify_cksum((char *)d, sizeof(struct xfs_dqblk),
XFS_DQUOT_CRC_OFF))
return false;
if (!uuid_equal(&d->dd_uuid, &mp->m_sb.sb_meta_uuid))
return false;
}
return true;
}
STATIC bool
xfs_dquot_buf_verify(
struct xfs_mount *mp,
struct xfs_buf *bp,
int warn)
{
struct xfs_dqblk *d = (struct xfs_dqblk *)bp->b_addr;
xfs_dqid_t id = 0;
int ndquots;
int i;
/*
* if we are in log recovery, the quota subsystem has not been
* initialised so we have no quotainfo structure. In that case, we need
* to manually calculate the number of dquots in the buffer.
*/
if (mp->m_quotainfo)
ndquots = mp->m_quotainfo->qi_dqperchunk;
else
ndquots = xfs_calc_dquots_per_chunk(bp->b_length);
/*
* On the first read of the buffer, verify that each dquot is valid.
* We don't know what the id of the dquot is supposed to be, just that
* they should be increasing monotonically within the buffer. If the
* first id is corrupt, then it will fail on the second dquot in the
* buffer so corruptions could point to the wrong dquot in this case.
*/
for (i = 0; i < ndquots; i++) {
struct xfs_disk_dquot *ddq;
int error;
ddq = &d[i].dd_diskdq;
if (i == 0)
id = be32_to_cpu(ddq->d_id);
error = xfs_dqcheck(mp, ddq, id + i, 0, warn, __func__);
if (error)
return false;
}
return true;
}
static void
xfs_dquot_buf_read_verify(
struct xfs_buf *bp)
{
struct xfs_mount *mp = bp->b_target->bt_mount;
if (!xfs_dquot_buf_verify_crc(mp, bp))
xfs_buf_ioerror(bp, -EFSBADCRC);
else if (!xfs_dquot_buf_verify(mp, bp, XFS_QMOPT_DOWARN))
xfs_buf_ioerror(bp, -EFSCORRUPTED);
if (bp->b_error)
xfs_verifier_error(bp);
}
/*
* readahead errors are silent and simply leave the buffer as !done so a real
* read will then be run with the xfs_dquot_buf_ops verifier. See
* xfs_inode_buf_verify() for why we use EIO and ~XBF_DONE here rather than
* reporting the failure.
*/
static void
xfs_dquot_buf_readahead_verify(
struct xfs_buf *bp)
{
struct xfs_mount *mp = bp->b_target->bt_mount;
if (!xfs_dquot_buf_verify_crc(mp, bp) ||
!xfs_dquot_buf_verify(mp, bp, 0)) {
xfs_buf_ioerror(bp, -EIO);
bp->b_flags &= ~XBF_DONE;
}
}
/*
* we don't calculate the CRC here as that is done when the dquot is flushed to
* the buffer after the update is done. This ensures that the dquot in the
* buffer always has an up-to-date CRC value.
*/
static void
xfs_dquot_buf_write_verify(
struct xfs_buf *bp)
{
struct xfs_mount *mp = bp->b_target->bt_mount;
if (!xfs_dquot_buf_verify(mp, bp, XFS_QMOPT_DOWARN)) {
xfs_buf_ioerror(bp, -EFSCORRUPTED);
xfs_verifier_error(bp);
return;
}
}
const struct xfs_buf_ops xfs_dquot_buf_ops = {
.name = "xfs_dquot",
.verify_read = xfs_dquot_buf_read_verify,
.verify_write = xfs_dquot_buf_write_verify,
};
const struct xfs_buf_ops xfs_dquot_buf_ra_ops = {
.name = "xfs_dquot_ra",
.verify_read = xfs_dquot_buf_readahead_verify,
.verify_write = xfs_dquot_buf_write_verify,
};
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