linux_dsm_epyc7002/fs/xfs/linux-2.6/xfs_sync.c
Dave Chinner 777df5afdb xfs: Make inode reclaim states explicit
A.K.A.: don't rely on xfs_iflush() return value in reclaim

We have gradually been moving checks out of the reclaim code because
they are duplicated in xfs_iflush(). We've had a history of problems
in this area, and many of them stem from the overloading of the
return values from xfs_iflush() and interaction with inode flush
locking to determine if the inode is safe to reclaim.

With the desire to move to delayed write flushing of inodes and
non-blocking inode tree reclaim walks, the overloading of the
return value of xfs_iflush makes it very difficult to determine
the correct thing to do next.

This patch explicitly re-adds the checks to the inode reclaim code,
removing the reliance on the return value of xfs_iflush() to
determine what to do next. It also means that we can clearly
document all the inode states that reclaim must handle and hence
we can easily see that we handled all the necessary cases.

This also removes the need for the xfs_inode_clean() check in
xfs_iflush() as all callers now check this first (safely).

Signed-off-by: Dave Chinner <david@fromorbit.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
2010-02-06 12:37:26 +11:00

812 lines
19 KiB
C

/*
* Copyright (c) 2000-2005 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
*/
#include "xfs.h"
#include "xfs_fs.h"
#include "xfs_types.h"
#include "xfs_bit.h"
#include "xfs_log.h"
#include "xfs_inum.h"
#include "xfs_trans.h"
#include "xfs_sb.h"
#include "xfs_ag.h"
#include "xfs_dir2.h"
#include "xfs_dmapi.h"
#include "xfs_mount.h"
#include "xfs_bmap_btree.h"
#include "xfs_alloc_btree.h"
#include "xfs_ialloc_btree.h"
#include "xfs_btree.h"
#include "xfs_dir2_sf.h"
#include "xfs_attr_sf.h"
#include "xfs_inode.h"
#include "xfs_dinode.h"
#include "xfs_error.h"
#include "xfs_mru_cache.h"
#include "xfs_filestream.h"
#include "xfs_vnodeops.h"
#include "xfs_utils.h"
#include "xfs_buf_item.h"
#include "xfs_inode_item.h"
#include "xfs_rw.h"
#include "xfs_quota.h"
#include "xfs_trace.h"
#include <linux/kthread.h>
#include <linux/freezer.h>
STATIC xfs_inode_t *
xfs_inode_ag_lookup(
struct xfs_mount *mp,
struct xfs_perag *pag,
uint32_t *first_index,
int tag)
{
int nr_found;
struct xfs_inode *ip;
/*
* use a gang lookup to find the next inode in the tree
* as the tree is sparse and a gang lookup walks to find
* the number of objects requested.
*/
if (tag == XFS_ICI_NO_TAG) {
nr_found = radix_tree_gang_lookup(&pag->pag_ici_root,
(void **)&ip, *first_index, 1);
} else {
nr_found = radix_tree_gang_lookup_tag(&pag->pag_ici_root,
(void **)&ip, *first_index, 1, tag);
}
if (!nr_found)
return NULL;
/*
* Update the index for the next lookup. Catch overflows
* into the next AG range which can occur if we have inodes
* in the last block of the AG and we are currently
* pointing to the last inode.
*/
*first_index = XFS_INO_TO_AGINO(mp, ip->i_ino + 1);
if (*first_index < XFS_INO_TO_AGINO(mp, ip->i_ino))
return NULL;
return ip;
}
STATIC int
xfs_inode_ag_walk(
struct xfs_mount *mp,
struct xfs_perag *pag,
int (*execute)(struct xfs_inode *ip,
struct xfs_perag *pag, int flags),
int flags,
int tag,
int exclusive)
{
uint32_t first_index;
int last_error = 0;
int skipped;
restart:
skipped = 0;
first_index = 0;
do {
int error = 0;
xfs_inode_t *ip;
if (exclusive)
write_lock(&pag->pag_ici_lock);
else
read_lock(&pag->pag_ici_lock);
ip = xfs_inode_ag_lookup(mp, pag, &first_index, tag);
if (!ip) {
if (exclusive)
write_unlock(&pag->pag_ici_lock);
else
read_unlock(&pag->pag_ici_lock);
break;
}
/* execute releases pag->pag_ici_lock */
error = execute(ip, pag, flags);
if (error == EAGAIN) {
skipped++;
continue;
}
if (error)
last_error = error;
/* bail out if the filesystem is corrupted. */
if (error == EFSCORRUPTED)
break;
} while (1);
if (skipped) {
delay(1);
goto restart;
}
return last_error;
}
int
xfs_inode_ag_iterator(
struct xfs_mount *mp,
int (*execute)(struct xfs_inode *ip,
struct xfs_perag *pag, int flags),
int flags,
int tag,
int exclusive)
{
int error = 0;
int last_error = 0;
xfs_agnumber_t ag;
for (ag = 0; ag < mp->m_sb.sb_agcount; ag++) {
struct xfs_perag *pag;
pag = xfs_perag_get(mp, ag);
if (!pag->pag_ici_init) {
xfs_perag_put(pag);
continue;
}
error = xfs_inode_ag_walk(mp, pag, execute, flags, tag,
exclusive);
xfs_perag_put(pag);
if (error) {
last_error = error;
if (error == EFSCORRUPTED)
break;
}
}
return XFS_ERROR(last_error);
}
/* must be called with pag_ici_lock held and releases it */
int
xfs_sync_inode_valid(
struct xfs_inode *ip,
struct xfs_perag *pag)
{
struct inode *inode = VFS_I(ip);
int error = EFSCORRUPTED;
/* nothing to sync during shutdown */
if (XFS_FORCED_SHUTDOWN(ip->i_mount))
goto out_unlock;
/* avoid new or reclaimable inodes. Leave for reclaim code to flush */
error = ENOENT;
if (xfs_iflags_test(ip, XFS_INEW | XFS_IRECLAIMABLE | XFS_IRECLAIM))
goto out_unlock;
/* If we can't grab the inode, it must on it's way to reclaim. */
if (!igrab(inode))
goto out_unlock;
if (is_bad_inode(inode)) {
IRELE(ip);
goto out_unlock;
}
/* inode is valid */
error = 0;
out_unlock:
read_unlock(&pag->pag_ici_lock);
return error;
}
STATIC int
xfs_sync_inode_data(
struct xfs_inode *ip,
struct xfs_perag *pag,
int flags)
{
struct inode *inode = VFS_I(ip);
struct address_space *mapping = inode->i_mapping;
int error = 0;
error = xfs_sync_inode_valid(ip, pag);
if (error)
return error;
if (!mapping_tagged(mapping, PAGECACHE_TAG_DIRTY))
goto out_wait;
if (!xfs_ilock_nowait(ip, XFS_IOLOCK_SHARED)) {
if (flags & SYNC_TRYLOCK)
goto out_wait;
xfs_ilock(ip, XFS_IOLOCK_SHARED);
}
error = xfs_flush_pages(ip, 0, -1, (flags & SYNC_WAIT) ?
0 : XBF_ASYNC, FI_NONE);
xfs_iunlock(ip, XFS_IOLOCK_SHARED);
out_wait:
if (flags & SYNC_WAIT)
xfs_ioend_wait(ip);
IRELE(ip);
return error;
}
STATIC int
xfs_sync_inode_attr(
struct xfs_inode *ip,
struct xfs_perag *pag,
int flags)
{
int error = 0;
error = xfs_sync_inode_valid(ip, pag);
if (error)
return error;
xfs_ilock(ip, XFS_ILOCK_SHARED);
if (xfs_inode_clean(ip))
goto out_unlock;
if (!xfs_iflock_nowait(ip)) {
if (!(flags & SYNC_WAIT))
goto out_unlock;
xfs_iflock(ip);
}
if (xfs_inode_clean(ip)) {
xfs_ifunlock(ip);
goto out_unlock;
}
error = xfs_iflush(ip, (flags & SYNC_WAIT) ?
XFS_IFLUSH_SYNC : XFS_IFLUSH_DELWRI);
out_unlock:
xfs_iunlock(ip, XFS_ILOCK_SHARED);
IRELE(ip);
return error;
}
/*
* Write out pagecache data for the whole filesystem.
*/
int
xfs_sync_data(
struct xfs_mount *mp,
int flags)
{
int error;
ASSERT((flags & ~(SYNC_TRYLOCK|SYNC_WAIT)) == 0);
error = xfs_inode_ag_iterator(mp, xfs_sync_inode_data, flags,
XFS_ICI_NO_TAG, 0);
if (error)
return XFS_ERROR(error);
xfs_log_force(mp, (flags & SYNC_WAIT) ? XFS_LOG_SYNC : 0);
return 0;
}
/*
* Write out inode metadata (attributes) for the whole filesystem.
*/
int
xfs_sync_attr(
struct xfs_mount *mp,
int flags)
{
ASSERT((flags & ~SYNC_WAIT) == 0);
return xfs_inode_ag_iterator(mp, xfs_sync_inode_attr, flags,
XFS_ICI_NO_TAG, 0);
}
STATIC int
xfs_commit_dummy_trans(
struct xfs_mount *mp,
uint flags)
{
struct xfs_inode *ip = mp->m_rootip;
struct xfs_trans *tp;
int error;
/*
* Put a dummy transaction in the log to tell recovery
* that all others are OK.
*/
tp = xfs_trans_alloc(mp, XFS_TRANS_DUMMY1);
error = xfs_trans_reserve(tp, 0, XFS_ICHANGE_LOG_RES(mp), 0, 0, 0);
if (error) {
xfs_trans_cancel(tp, 0);
return error;
}
xfs_ilock(ip, XFS_ILOCK_EXCL);
xfs_trans_ijoin(tp, ip, XFS_ILOCK_EXCL);
xfs_trans_ihold(tp, ip);
xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
error = xfs_trans_commit(tp, 0);
xfs_iunlock(ip, XFS_ILOCK_EXCL);
/* the log force ensures this transaction is pushed to disk */
xfs_log_force(mp, (flags & SYNC_WAIT) ? XFS_LOG_SYNC : 0);
return error;
}
STATIC int
xfs_sync_fsdata(
struct xfs_mount *mp,
int flags)
{
struct xfs_buf *bp;
struct xfs_buf_log_item *bip;
int error = 0;
/*
* If this is xfssyncd() then only sync the superblock if we can
* lock it without sleeping and it is not pinned.
*/
if (flags & SYNC_TRYLOCK) {
ASSERT(!(flags & SYNC_WAIT));
bp = xfs_getsb(mp, XBF_TRYLOCK);
if (!bp)
goto out;
bip = XFS_BUF_FSPRIVATE(bp, struct xfs_buf_log_item *);
if (!bip || !xfs_buf_item_dirty(bip) || XFS_BUF_ISPINNED(bp))
goto out_brelse;
} else {
bp = xfs_getsb(mp, 0);
/*
* If the buffer is pinned then push on the log so we won't
* get stuck waiting in the write for someone, maybe
* ourselves, to flush the log.
*
* Even though we just pushed the log above, we did not have
* the superblock buffer locked at that point so it can
* become pinned in between there and here.
*/
if (XFS_BUF_ISPINNED(bp))
xfs_log_force(mp, 0);
}
if (flags & SYNC_WAIT)
XFS_BUF_UNASYNC(bp);
else
XFS_BUF_ASYNC(bp);
error = xfs_bwrite(mp, bp);
if (error)
return error;
/*
* If this is a data integrity sync make sure all pending buffers
* are flushed out for the log coverage check below.
*/
if (flags & SYNC_WAIT)
xfs_flush_buftarg(mp->m_ddev_targp, 1);
if (xfs_log_need_covered(mp))
error = xfs_commit_dummy_trans(mp, flags);
return error;
out_brelse:
xfs_buf_relse(bp);
out:
return error;
}
/*
* When remounting a filesystem read-only or freezing the filesystem, we have
* two phases to execute. This first phase is syncing the data before we
* quiesce the filesystem, and the second is flushing all the inodes out after
* we've waited for all the transactions created by the first phase to
* complete. The second phase ensures that the inodes are written to their
* location on disk rather than just existing in transactions in the log. This
* means after a quiesce there is no log replay required to write the inodes to
* disk (this is the main difference between a sync and a quiesce).
*/
/*
* First stage of freeze - no writers will make progress now we are here,
* so we flush delwri and delalloc buffers here, then wait for all I/O to
* complete. Data is frozen at that point. Metadata is not frozen,
* transactions can still occur here so don't bother flushing the buftarg
* because it'll just get dirty again.
*/
int
xfs_quiesce_data(
struct xfs_mount *mp)
{
int error;
/* push non-blocking */
xfs_sync_data(mp, 0);
xfs_qm_sync(mp, SYNC_TRYLOCK);
/* push and block till complete */
xfs_sync_data(mp, SYNC_WAIT);
xfs_qm_sync(mp, SYNC_WAIT);
/* write superblock and hoover up shutdown errors */
error = xfs_sync_fsdata(mp, SYNC_WAIT);
/* flush data-only devices */
if (mp->m_rtdev_targp)
XFS_bflush(mp->m_rtdev_targp);
return error;
}
STATIC void
xfs_quiesce_fs(
struct xfs_mount *mp)
{
int count = 0, pincount;
xfs_flush_buftarg(mp->m_ddev_targp, 0);
xfs_reclaim_inodes(mp, XFS_IFLUSH_DELWRI_ELSE_ASYNC);
/*
* This loop must run at least twice. The first instance of the loop
* will flush most meta data but that will generate more meta data
* (typically directory updates). Which then must be flushed and
* logged before we can write the unmount record.
*/
do {
xfs_sync_attr(mp, SYNC_WAIT);
pincount = xfs_flush_buftarg(mp->m_ddev_targp, 1);
if (!pincount) {
delay(50);
count++;
}
} while (count < 2);
}
/*
* Second stage of a quiesce. The data is already synced, now we have to take
* care of the metadata. New transactions are already blocked, so we need to
* wait for any remaining transactions to drain out before proceding.
*/
void
xfs_quiesce_attr(
struct xfs_mount *mp)
{
int error = 0;
/* wait for all modifications to complete */
while (atomic_read(&mp->m_active_trans) > 0)
delay(100);
/* flush inodes and push all remaining buffers out to disk */
xfs_quiesce_fs(mp);
/*
* Just warn here till VFS can correctly support
* read-only remount without racing.
*/
WARN_ON(atomic_read(&mp->m_active_trans) != 0);
/* Push the superblock and write an unmount record */
error = xfs_log_sbcount(mp, 1);
if (error)
xfs_fs_cmn_err(CE_WARN, mp,
"xfs_attr_quiesce: failed to log sb changes. "
"Frozen image may not be consistent.");
xfs_log_unmount_write(mp);
xfs_unmountfs_writesb(mp);
}
/*
* Enqueue a work item to be picked up by the vfs xfssyncd thread.
* Doing this has two advantages:
* - It saves on stack space, which is tight in certain situations
* - It can be used (with care) as a mechanism to avoid deadlocks.
* Flushing while allocating in a full filesystem requires both.
*/
STATIC void
xfs_syncd_queue_work(
struct xfs_mount *mp,
void *data,
void (*syncer)(struct xfs_mount *, void *),
struct completion *completion)
{
struct xfs_sync_work *work;
work = kmem_alloc(sizeof(struct xfs_sync_work), KM_SLEEP);
INIT_LIST_HEAD(&work->w_list);
work->w_syncer = syncer;
work->w_data = data;
work->w_mount = mp;
work->w_completion = completion;
spin_lock(&mp->m_sync_lock);
list_add_tail(&work->w_list, &mp->m_sync_list);
spin_unlock(&mp->m_sync_lock);
wake_up_process(mp->m_sync_task);
}
/*
* Flush delayed allocate data, attempting to free up reserved space
* from existing allocations. At this point a new allocation attempt
* has failed with ENOSPC and we are in the process of scratching our
* heads, looking about for more room...
*/
STATIC void
xfs_flush_inodes_work(
struct xfs_mount *mp,
void *arg)
{
struct inode *inode = arg;
xfs_sync_data(mp, SYNC_TRYLOCK);
xfs_sync_data(mp, SYNC_TRYLOCK | SYNC_WAIT);
iput(inode);
}
void
xfs_flush_inodes(
xfs_inode_t *ip)
{
struct inode *inode = VFS_I(ip);
DECLARE_COMPLETION_ONSTACK(completion);
igrab(inode);
xfs_syncd_queue_work(ip->i_mount, inode, xfs_flush_inodes_work, &completion);
wait_for_completion(&completion);
xfs_log_force(ip->i_mount, XFS_LOG_SYNC);
}
/*
* Every sync period we need to unpin all items, reclaim inodes, sync
* quota and write out the superblock. We might need to cover the log
* to indicate it is idle.
*/
STATIC void
xfs_sync_worker(
struct xfs_mount *mp,
void *unused)
{
int error;
if (!(mp->m_flags & XFS_MOUNT_RDONLY)) {
xfs_log_force(mp, 0);
xfs_reclaim_inodes(mp, XFS_IFLUSH_DELWRI_ELSE_ASYNC);
/* dgc: errors ignored here */
error = xfs_qm_sync(mp, SYNC_TRYLOCK);
error = xfs_sync_fsdata(mp, SYNC_TRYLOCK);
}
mp->m_sync_seq++;
wake_up(&mp->m_wait_single_sync_task);
}
STATIC int
xfssyncd(
void *arg)
{
struct xfs_mount *mp = arg;
long timeleft;
xfs_sync_work_t *work, *n;
LIST_HEAD (tmp);
set_freezable();
timeleft = xfs_syncd_centisecs * msecs_to_jiffies(10);
for (;;) {
timeleft = schedule_timeout_interruptible(timeleft);
/* swsusp */
try_to_freeze();
if (kthread_should_stop() && list_empty(&mp->m_sync_list))
break;
spin_lock(&mp->m_sync_lock);
/*
* We can get woken by laptop mode, to do a sync -
* that's the (only!) case where the list would be
* empty with time remaining.
*/
if (!timeleft || list_empty(&mp->m_sync_list)) {
if (!timeleft)
timeleft = xfs_syncd_centisecs *
msecs_to_jiffies(10);
INIT_LIST_HEAD(&mp->m_sync_work.w_list);
list_add_tail(&mp->m_sync_work.w_list,
&mp->m_sync_list);
}
list_for_each_entry_safe(work, n, &mp->m_sync_list, w_list)
list_move(&work->w_list, &tmp);
spin_unlock(&mp->m_sync_lock);
list_for_each_entry_safe(work, n, &tmp, w_list) {
(*work->w_syncer)(mp, work->w_data);
list_del(&work->w_list);
if (work == &mp->m_sync_work)
continue;
if (work->w_completion)
complete(work->w_completion);
kmem_free(work);
}
}
return 0;
}
int
xfs_syncd_init(
struct xfs_mount *mp)
{
mp->m_sync_work.w_syncer = xfs_sync_worker;
mp->m_sync_work.w_mount = mp;
mp->m_sync_work.w_completion = NULL;
mp->m_sync_task = kthread_run(xfssyncd, mp, "xfssyncd");
if (IS_ERR(mp->m_sync_task))
return -PTR_ERR(mp->m_sync_task);
return 0;
}
void
xfs_syncd_stop(
struct xfs_mount *mp)
{
kthread_stop(mp->m_sync_task);
}
void
__xfs_inode_set_reclaim_tag(
struct xfs_perag *pag,
struct xfs_inode *ip)
{
radix_tree_tag_set(&pag->pag_ici_root,
XFS_INO_TO_AGINO(ip->i_mount, ip->i_ino),
XFS_ICI_RECLAIM_TAG);
}
/*
* We set the inode flag atomically with the radix tree tag.
* Once we get tag lookups on the radix tree, this inode flag
* can go away.
*/
void
xfs_inode_set_reclaim_tag(
xfs_inode_t *ip)
{
struct xfs_mount *mp = ip->i_mount;
struct xfs_perag *pag;
pag = xfs_perag_get(mp, XFS_INO_TO_AGNO(mp, ip->i_ino));
read_lock(&pag->pag_ici_lock);
spin_lock(&ip->i_flags_lock);
__xfs_inode_set_reclaim_tag(pag, ip);
__xfs_iflags_set(ip, XFS_IRECLAIMABLE);
spin_unlock(&ip->i_flags_lock);
read_unlock(&pag->pag_ici_lock);
xfs_perag_put(pag);
}
void
__xfs_inode_clear_reclaim_tag(
xfs_mount_t *mp,
xfs_perag_t *pag,
xfs_inode_t *ip)
{
radix_tree_tag_clear(&pag->pag_ici_root,
XFS_INO_TO_AGINO(mp, ip->i_ino), XFS_ICI_RECLAIM_TAG);
}
/*
* Inodes in different states need to be treated differently, and the return
* value of xfs_iflush is not sufficient to get this right. The following table
* lists the inode states and the reclaim actions necessary for non-blocking
* reclaim:
*
*
* inode state iflush ret required action
* --------------- ---------- ---------------
* bad - reclaim
* shutdown EIO unpin and reclaim
* clean, unpinned 0 reclaim
* stale, unpinned 0 reclaim
* clean, pinned(*) 0 unpin and reclaim
* stale, pinned 0 unpin and reclaim
* dirty, async 0 block on flush lock, reclaim
* dirty, sync flush 0 block on flush lock, reclaim
*
* (*) dgc: I don't think the clean, pinned state is possible but it gets
* handled anyway given the order of checks implemented.
*
* Hence the order of actions after gaining the locks should be:
* bad => reclaim
* shutdown => unpin and reclaim
* pinned => unpin
* stale => reclaim
* clean => reclaim
* dirty => flush, wait and reclaim
*/
STATIC int
xfs_reclaim_inode(
struct xfs_inode *ip,
struct xfs_perag *pag,
int sync_mode)
{
int error;
/*
* The radix tree lock here protects a thread in xfs_iget from racing
* with us starting reclaim on the inode. Once we have the
* XFS_IRECLAIM flag set it will not touch us.
*/
spin_lock(&ip->i_flags_lock);
ASSERT_ALWAYS(__xfs_iflags_test(ip, XFS_IRECLAIMABLE));
if (__xfs_iflags_test(ip, XFS_IRECLAIM)) {
/* ignore as it is already under reclaim */
spin_unlock(&ip->i_flags_lock);
write_unlock(&pag->pag_ici_lock);
return 0;
}
__xfs_iflags_set(ip, XFS_IRECLAIM);
spin_unlock(&ip->i_flags_lock);
write_unlock(&pag->pag_ici_lock);
xfs_ilock(ip, XFS_ILOCK_EXCL);
xfs_iflock(ip);
if (is_bad_inode(VFS_I(ip)))
goto reclaim;
if (XFS_FORCED_SHUTDOWN(ip->i_mount)) {
xfs_iunpin_wait(ip);
goto reclaim;
}
if (xfs_ipincount(ip))
xfs_iunpin_wait(ip);
if (xfs_iflags_test(ip, XFS_ISTALE))
goto reclaim;
if (xfs_inode_clean(ip))
goto reclaim;
/* Now we have an inode that needs flushing */
error = xfs_iflush(ip, sync_mode);
if (!error) {
switch(sync_mode) {
case XFS_IFLUSH_DELWRI_ELSE_ASYNC:
case XFS_IFLUSH_DELWRI:
case XFS_IFLUSH_ASYNC:
case XFS_IFLUSH_DELWRI_ELSE_SYNC:
case XFS_IFLUSH_SYNC:
/* IO issued, synchronise with IO completion */
xfs_iflock(ip);
break;
default:
ASSERT(0);
break;
}
}
reclaim:
xfs_ifunlock(ip);
xfs_iunlock(ip, XFS_ILOCK_EXCL);
xfs_ireclaim(ip);
return 0;
}
int
xfs_reclaim_inodes(
xfs_mount_t *mp,
int mode)
{
return xfs_inode_ag_iterator(mp, xfs_reclaim_inode, mode,
XFS_ICI_RECLAIM_TAG, 1);
}