[PATCH 07/28] xfs: split xfs_itruncate_finish

Christoph Hellwig
2011-07-07T11:06:45Z

[-- Attachment #1: xfs-split-xfs_itruncate_finish --]
[-- Type: text/plain, Size: 22357 bytes --]

Split the guts of xfs_itruncate_finish that loop over the existing extents
and calls xfs_bunmapi on them into a new helper, xfs_itruncate_externs.
Make xfs_attr_inactive call it directly instead of xfs_itruncate_finish,
which allows to simplify the latter a lot, by only letting it deal with
the data fork. As a result xfs_itruncate_finish is renamed to
xfs_itruncate_data to make its use case more obvious.

Also remove the sync parameter from xfs_itruncate_data, which has been
unessecary since the introduction of the busy extent list in 2002, and
completely dead code since 2003 when the XFS_BMAPI_ASYNC parameter was
made a no-op.

I can't actually see why the xfs_attr_inactive needs to set the transaction
sync, but let's keep this patch simple and without changes in behaviour.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Alex Elder <aelder@sgi.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>

Index: xfs/fs/xfs/linux-2.6/xfs_iops.c
===================================================================
--- xfs.orig/fs/xfs/linux-2.6/xfs_iops.c 2011-07-05 13:36:54.099349132 +0200
+++ xfs/fs/xfs/linux-2.6/xfs_iops.c 2011-07-05 13:36:57.105999510 +0200
@@ -879,15 +879,7 @@ xfs_setattr_size(
ip->i_size = iattr->ia_size;
} else if (iattr->ia_size <= ip->i_size ||
(iattr->ia_size == 0 && ip->i_d.di_nextents)) {
- /*
- * Signal a sync transaction unless we are truncating an
- * already unlinked file on a wsync filesystem.
- */
- error = xfs_itruncate_finish(&tp, ip, iattr->ia_size,
- XFS_DATA_FORK,
- ((ip->i_d.di_nlink != 0 ||
- !(mp->m_flags & XFS_MOUNT_WSYNC))
- ? 1 : 0));
+ error = xfs_itruncate_data(&tp, ip, iattr->ia_size);
if (error)
goto out_trans_abort;

Index: xfs/fs/xfs/quota/xfs_qm_syscalls.c
===================================================================
--- xfs.orig/fs/xfs/quota/xfs_qm_syscalls.c 2011-07-05 13:36:47.676050597 +0200
+++ xfs/fs/xfs/quota/xfs_qm_syscalls.c 2011-07-05 13:36:57.109332826 +0200
@@ -263,7 +263,7 @@ xfs_qm_scall_trunc_qfile(
xfs_ilock(ip, XFS_ILOCK_EXCL);
xfs_trans_ijoin(tp, ip);

- error = xfs_itruncate_finish(&tp, ip, 0, XFS_DATA_FORK, 1);
+ error = xfs_itruncate_data(&tp, ip, 0);
if (error) {
xfs_trans_cancel(tp, XFS_TRANS_RELEASE_LOG_RES |
XFS_TRANS_ABORT);
Index: xfs/fs/xfs/xfs_attr.c
===================================================================
--- xfs.orig/fs/xfs/xfs_attr.c 2011-07-05 13:36:47.689383857 +0200
+++ xfs/fs/xfs/xfs_attr.c 2011-07-05 13:36:57.109332826 +0200
@@ -822,17 +822,21 @@ xfs_attr_inactive(xfs_inode_t *dp)
error = xfs_attr_root_inactive(&trans, dp);
if (error)
goto out;
+
/*
- * signal synchronous inactive transactions unless this
- * is a synchronous mount filesystem in which case we
- * know that we're here because we've been called out of
- * xfs_inactive which means that the last reference is gone
- * and the unlink transaction has already hit the disk so
- * async inactive transactions are safe.
+ * Signal synchronous inactive transactions unless this is a
+ * synchronous mount filesystem in which case we know that we're here
+ * because we've been called out of xfs_inactive which means that the
+ * last reference is gone and the unlink transaction has already hit
+ * the disk so async inactive transactions are safe.
*/
- if ((error = xfs_itruncate_finish(&trans, dp, 0LL, XFS_ATTR_FORK,
- (!(mp->m_flags & XFS_MOUNT_WSYNC)
- ? 1 : 0))))
+ if (!(mp->m_flags & XFS_MOUNT_WSYNC)) {
+ if (dp->i_d.di_anextents > 0)
+ xfs_trans_set_sync(trans);
+ }
+
+ error = xfs_itruncate_extents(&trans, dp, XFS_ATTR_FORK, 0);
+ if (error)
goto out;

/*
Index: xfs/fs/xfs/xfs_inode.c
===================================================================
--- xfs.orig/fs/xfs/xfs_inode.c 2011-07-05 13:36:54.586013161 +0200
+++ xfs/fs/xfs/xfs_inode.c 2011-07-05 13:38:16.342236914 +0200
@@ -52,7 +52,7 @@ kmem_zone_t *xfs_ifork_zone;
kmem_zone_t *xfs_inode_zone;

/*
- * Used in xfs_itruncate(). This is the maximum number of extents
+ * Used in xfs_itruncate_extents(). This is the maximum number of extents
* freed from a file in a single transaction.
*/
#define XFS_ITRUNC_MAX_EXTENTS 2
@@ -1217,8 +1217,9 @@ xfs_isize_check(
#endif /* DEBUG */

/*
- * Free up the underlying blocks past new_size. The new size must be
- * smaller than the current size.
+ * Free up the underlying blocks past new_size. The new size must be smaller
+ * than the current size. This routine can be used both for the attribute and
+ * data fork, and does not modify the inode size, which is left to the caller.
*
* The transaction passed to this routine must have made a permanent log
* reservation of at least XFS_ITRUNCATE_LOG_RES. This routine may commit the
@@ -1230,31 +1231,6 @@ xfs_isize_check(
* will be "held" within the returned transaction. This routine does NOT
* require any disk space to be reserved for it within the transaction.
*
- * The fork parameter must be either XFS_ATTR_FORK or XFS_DATA_FORK, and it
- * indicates the fork which is to be truncated. For the attribute fork we only
- * support truncation to size 0.
- *
- * We use the sync parameter to indicate whether or not the first transaction
- * we perform might have to be synchronous. For the attr fork, it needs to be
- * so if the unlink of the inode is not yet known to be permanent in the log.
- * This keeps us from freeing and reusing the blocks of the attribute fork
- * before the unlink of the inode becomes permanent.
- *
- * For the data fork, we normally have to run synchronously if we're being
- * called out of the inactive path or we're being called out of the create path
- * where we're truncating an existing file. Either way, the truncate needs to
- * be sync so blocks don't reappear in the file with altered data in case of a
- * crash. wsync filesystems can run the first case async because anything that
- * shrinks the inode has to run sync so by the time we're called here from
- * inactive, the inode size is permanently set to 0.
- *
- * Calls from the truncate path always need to be sync unless we're in a wsync
- * filesystem and the file has already been unlinked.
- *
- * The caller is responsible for correctly setting the sync parameter. It gets
- * too hard for us to guess here which path we're being called out of just
- * based on inode state.
- *
* If we get an error, we must return with the inode locked and linked into the
* current transaction. This keeps things simple for the higher level code,
* because it always knows that the inode is locked and held in the transaction
@@ -1262,124 +1238,31 @@ xfs_isize_check(
* dirty on error so that transactions can be easily aborted if possible.
*/
int
-xfs_itruncate_finish(
- xfs_trans_t **tp,
- xfs_inode_t *ip,
- xfs_fsize_t new_size,
- int fork,
- int sync)
+xfs_itruncate_extents(
+ struct xfs_trans **tpp,
+ struct xfs_inode *ip,
+ int whichfork,
+ xfs_fsize_t new_size)
{
- xfs_fsblock_t first_block;
- xfs_fileoff_t first_unmap_block;
- xfs_fileoff_t last_block;
- xfs_filblks_t unmap_len=0;
- xfs_mount_t *mp;
- xfs_trans_t *ntp;
- int done;
- int committed;
- xfs_bmap_free_t free_list;
- int error;
+ struct xfs_mount *mp = ip->i_mount;
+ struct xfs_trans *tp = *tpp;
+ struct xfs_trans *ntp;
+ xfs_bmap_free_t free_list;
+ xfs_fsblock_t first_block;
+ xfs_fileoff_t first_unmap_block;
+ xfs_fileoff_t last_block;
+ xfs_filblks_t unmap_len;
+ int committed;
+ int error = 0;
+ int done = 0;

ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL|XFS_IOLOCK_EXCL));
- ASSERT((new_size == 0) || (new_size <= ip->i_size));
- ASSERT(*tp != NULL);
- ASSERT((*tp)->t_flags & XFS_TRANS_PERM_LOG_RES);
- ASSERT(ip->i_transp == *tp);
+ ASSERT(new_size <= ip->i_size);
+ ASSERT(tp->t_flags & XFS_TRANS_PERM_LOG_RES);
+ ASSERT(ip->i_transp == tp);
ASSERT(ip->i_itemp != NULL);
ASSERT(ip->i_itemp->ili_lock_flags == 0);
-
-
- ntp = *tp;
- mp = (ntp)->t_mountp;
- ASSERT(! XFS_NOT_DQATTACHED(mp, ip));
-
- /*
- * We only support truncating the entire attribute fork.
- */
- if (fork == XFS_ATTR_FORK) {
- new_size = 0LL;
- }
- first_unmap_block = XFS_B_TO_FSB(mp, (xfs_ufsize_t)new_size);
- trace_xfs_itruncate_finish_start(ip, new_size);
-
- /*
- * The first thing we do is set the size to new_size permanently
- * on disk. This way we don't have to worry about anyone ever
- * being able to look at the data being freed even in the face
- * of a crash. What we're getting around here is the case where
- * we free a block, it is allocated to another file, it is written
- * to, and then we crash. If the new data gets written to the
- * file but the log buffers containing the free and reallocation
- * don't, then we'd end up with garbage in the blocks being freed.
- * As long as we make the new_size permanent before actually
- * freeing any blocks it doesn't matter if they get written to.
- *
- * The callers must signal into us whether or not the size
- * setting here must be synchronous. There are a few cases
- * where it doesn't have to be synchronous. Those cases
- * occur if the file is unlinked and we know the unlink is
- * permanent or if the blocks being truncated are guaranteed
- * to be beyond the inode eof (regardless of the link count)
- * and the eof value is permanent. Both of these cases occur
- * only on wsync-mounted filesystems. In those cases, we're
- * guaranteed that no user will ever see the data in the blocks
- * that are being truncated so the truncate can run async.
- * In the free beyond eof case, the file may wind up with
- * more blocks allocated to it than it needs if we crash
- * and that won't get fixed until the next time the file
- * is re-opened and closed but that's ok as that shouldn't
- * be too many blocks.
- *
- * However, we can't just make all wsync xactions run async
- * because there's one call out of the create path that needs
- * to run sync where it's truncating an existing file to size
- * 0 whose size is > 0.
- *
- * It's probably possible to come up with a test in this
- * routine that would correctly distinguish all the above
- * cases from the values of the function parameters and the
- * inode state but for sanity's sake, I've decided to let the
- * layers above just tell us. It's simpler to correctly figure
- * out in the layer above exactly under what conditions we
- * can run async and I think it's easier for others read and
- * follow the logic in case something has to be changed.
- * cscope is your friend -- rcc.
- *
- * The attribute fork is much simpler.
- *
- * For the attribute fork we allow the caller to tell us whether
- * the unlink of the inode that led to this call is yet permanent
- * in the on disk log. If it is not and we will be freeing extents
- * in this inode then we make the first transaction synchronous
- * to make sure that the unlink is permanent by the time we free
- * the blocks.
- */
- if (fork == XFS_DATA_FORK) {
- if (ip->i_d.di_nextents > 0) {
- /*
- * If we are not changing the file size then do
- * not update the on-disk file size - we may be
- * called from xfs_inactive_free_eofblocks(). If we
- * update the on-disk file size and then the system
- * crashes before the contents of the file are
- * flushed to disk then the files may be full of
- * holes (ie NULL files bug).
- */
- if (ip->i_size != new_size) {
- ip->i_d.di_size = new_size;
- ip->i_size = new_size;
- xfs_trans_log_inode(ntp, ip, XFS_ILOG_CORE);
- }
- }
- } else if (sync) {
- ASSERT(!(mp->m_flags & XFS_MOUNT_WSYNC));
- if (ip->i_d.di_anextents > 0)
- xfs_trans_set_sync(ntp);
- }
- ASSERT(fork == XFS_DATA_FORK ||
- (fork == XFS_ATTR_FORK &&
- ((sync && !(mp->m_flags & XFS_MOUNT_WSYNC)) ||
- (sync == 0 && (mp->m_flags & XFS_MOUNT_WSYNC)))));
+ ASSERT(!XFS_NOT_DQATTACHED(mp, ip));

/*
* Since it is possible for space to become allocated beyond
@@ -1390,128 +1273,143 @@ xfs_itruncate_finish(
* beyond the maximum file size (ie it is the same as last_block),
* then there is nothing to do.
*/
+ first_unmap_block = XFS_B_TO_FSB(mp, (xfs_ufsize_t)new_size);
last_block = XFS_B_TO_FSB(mp, (xfs_ufsize_t)XFS_MAXIOFFSET(mp));
- ASSERT(first_unmap_block <= last_block);
- done = 0;
- if (last_block == first_unmap_block) {
- done = 1;
- } else {
- unmap_len = last_block - first_unmap_block + 1;
- }
+ if (first_unmap_block == last_block)
+ return 0;
+
+ ASSERT(first_unmap_block < last_block);
+ unmap_len = last_block - first_unmap_block + 1;
while (!done) {
- /*
- * Free up up to XFS_ITRUNC_MAX_EXTENTS. xfs_bunmapi()
- * will tell us whether it freed the entire range or
- * not. If this is a synchronous mount (wsync),
- * then we can tell bunmapi to keep all the
- * transactions asynchronous since the unlink
- * transaction that made this inode inactive has
- * already hit the disk. There's no danger of
- * the freed blocks being reused, there being a
- * crash, and the reused blocks suddenly reappearing
- * in this file with garbage in them once recovery
- * runs.
- */
xfs_bmap_init(&free_list, &first_block);
- error = xfs_bunmapi(ntp, ip,
+ error = xfs_bunmapi(tp, ip,
first_unmap_block, unmap_len,
- xfs_bmapi_aflag(fork),
+ xfs_bmapi_aflag(whichfork),
XFS_ITRUNC_MAX_EXTENTS,
&first_block, &free_list,
&done);
- if (error) {
- /*
- * If the bunmapi call encounters an error,
- * return to the caller where the transaction
- * can be properly aborted. We just need to
- * make sure we're not holding any resources
- * that we were not when we came in.
- */
- xfs_bmap_cancel(&free_list);
- return error;
- }
+ if (error)
+ goto out_bmap_cancel;

/*
* Duplicate the transaction that has the permanent
* reservation and commit the old transaction.
*/
- error = xfs_bmap_finish(tp, &free_list, &committed);
- ntp = *tp;
+ error = xfs_bmap_finish(&tp, &free_list, &committed);
if (committed)
- xfs_trans_ijoin(ntp, ip);
-
- if (error) {
- /*
- * If the bmap finish call encounters an error, return
- * to the caller where the transaction can be properly
- * aborted. We just need to make sure we're not
- * holding any resources that we were not when we came
- * in.
- *
- * Aborting from this point might lose some blocks in
- * the file system, but oh well.
- */
- xfs_bmap_cancel(&free_list);
- return error;
- }
+ xfs_trans_ijoin(tp, ip);
+ if (error)
+ goto out_bmap_cancel;

if (committed) {
/*
* Mark the inode dirty so it will be logged and
* moved forward in the log as part of every commit.
*/
- xfs_trans_log_inode(ntp, ip, XFS_ILOG_CORE);
+ xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
}

- ntp = xfs_trans_dup(ntp);
- error = xfs_trans_commit(*tp, 0);
- *tp = ntp;
+ ntp = xfs_trans_dup(tp);
+ error = xfs_trans_commit(tp, 0);
+ tp = ntp;

- xfs_trans_ijoin(ntp, ip);
+ xfs_trans_ijoin(tp, ip);

if (error)
- return error;
+ goto out;
+
/*
- * transaction commit worked ok so we can drop the extra ticket
+ * Transaction commit worked ok so we can drop the extra ticket
* reference that we gained in xfs_trans_dup()
*/
- xfs_log_ticket_put(ntp->t_ticket);
- error = xfs_trans_reserve(ntp, 0,
+ xfs_log_ticket_put(tp->t_ticket);
+ error = xfs_trans_reserve(tp, 0,
XFS_ITRUNCATE_LOG_RES(mp), 0,
XFS_TRANS_PERM_LOG_RES,
XFS_ITRUNCATE_LOG_COUNT);
if (error)
- return error;
+ goto out;
}
+
+out:
+ *tpp = tp;
+ return error;
+out_bmap_cancel:
+ /*
+ * If the bunmapi call encounters an error, return to the caller where
+ * the transaction can be properly aborted. We just need to make sure
+ * we're not holding any resources that we were not when we came in.
+ */
+ xfs_bmap_cancel(&free_list);
+ goto out;
+}
+
+int
+xfs_itruncate_data(
+ struct xfs_trans **tpp,
+ struct xfs_inode *ip,
+ xfs_fsize_t new_size)
+{
+ struct xfs_mount *mp = ip->i_mount;
+ int error;
+
+ trace_xfs_itruncate_data_start(ip, new_size);
+
/*
- * Only update the size in the case of the data fork, but
- * always re-log the inode so that our permanent transaction
- * can keep on rolling it forward in the log.
+ * The first thing we do is set the size to new_size permanently on
+ * disk. This way we don't have to worry about anyone ever being able
+ * to look at the data being freed even in the face of a crash.
+ * What we're getting around here is the case where we free a block, it
+ * is allocated to another file, it is written to, and then we crash.
+ * If the new data gets written to the file but the log buffers
+ * containing the free and reallocation don't, then we'd end up with
+ * garbage in the blocks being freed. As long as we make the new_size
+ * permanent before actually freeing any blocks it doesn't matter if
+ * they get written to.
*/
- if (fork == XFS_DATA_FORK) {
- xfs_isize_check(mp, ip, new_size);
+ if (ip->i_d.di_nextents > 0) {
/*
- * If we are not changing the file size then do
- * not update the on-disk file size - we may be
- * called from xfs_inactive_free_eofblocks(). If we
- * update the on-disk file size and then the system
- * crashes before the contents of the file are
- * flushed to disk then the files may be full of
- * holes (ie NULL files bug).
+ * If we are not changing the file size then do not update
+ * the on-disk file size - we may be called from
+ * xfs_inactive_free_eofblocks(). If we update the on-disk
+ * file size and then the system crashes before the contents
+ * of the file are flushed to disk then the files may be
+ * full of holes (ie NULL files bug).
*/
if (ip->i_size != new_size) {
ip->i_d.di_size = new_size;
ip->i_size = new_size;
+ xfs_trans_log_inode(*tpp, ip, XFS_ILOG_CORE);
}
}
- xfs_trans_log_inode(ntp, ip, XFS_ILOG_CORE);
- ASSERT((new_size != 0) ||
- (fork == XFS_ATTR_FORK) ||
- (ip->i_delayed_blks == 0));
- ASSERT((new_size != 0) ||
- (fork == XFS_ATTR_FORK) ||
- (ip->i_d.di_nextents == 0));
- trace_xfs_itruncate_finish_end(ip, new_size);
+
+ error = xfs_itruncate_extents(tpp, ip, XFS_DATA_FORK, new_size);
+ if (error)
+ return error;
+
+ /*
+ * If we are not changing the file size then do not update the on-disk
+ * file size - we may be called from xfs_inactive_free_eofblocks().
+ * If we update the on-disk file size and then the system crashes
+ * before the contents of the file are flushed to disk then the files
+ * may be full of holes (ie NULL files bug).
+ */
+ xfs_isize_check(mp, ip, new_size);
+ if (ip->i_size != new_size) {
+ ip->i_d.di_size = new_size;
+ ip->i_size = new_size;
+ }
+
+ ASSERT(new_size != 0 || ip->i_delayed_blks == 0);
+ ASSERT(new_size != 0 || ip->i_d.di_nextents == 0);
+
+ /*
+ * Always re-log the inode so that our permanent transaction can keep
+ * on rolling it forward in the log.
+ */
+ xfs_trans_log_inode(*tpp, ip, XFS_ILOG_CORE);
+
+ trace_xfs_itruncate_data_end(ip, new_size);
return 0;
}

Index: xfs/fs/xfs/xfs_inode.h
===================================================================
--- xfs.orig/fs/xfs/xfs_inode.h 2011-07-05 13:36:54.592679793 +0200
+++ xfs/fs/xfs/xfs_inode.h 2011-07-05 13:36:57.112666141 +0200
@@ -491,8 +491,10 @@ uint xfs_ip2xflags(struct xfs_inode *);
uint xfs_dic2xflags(struct xfs_dinode *);
int xfs_ifree(struct xfs_trans *, xfs_inode_t *,
struct xfs_bmap_free *);
-int xfs_itruncate_finish(struct xfs_trans **, xfs_inode_t *,
- xfs_fsize_t, int, int);
+int xfs_itruncate_extents(struct xfs_trans **, struct xfs_inode *,
+ int, xfs_fsize_t);
+int xfs_itruncate_data(struct xfs_trans **, struct xfs_inode *,
+ xfs_fsize_t);
int xfs_iunlink(struct xfs_trans *, xfs_inode_t *);

void xfs_iext_realloc(xfs_inode_t *, int, int);
Index: xfs/fs/xfs/xfs_vnodeops.c
===================================================================
--- xfs.orig/fs/xfs/xfs_vnodeops.c 2011-07-05 13:36:54.589346477 +0200
+++ xfs/fs/xfs/xfs_vnodeops.c 2011-07-05 13:36:57.115999456 +0200
@@ -220,15 +220,12 @@ xfs_free_eofblocks(
xfs_ilock(ip, XFS_ILOCK_EXCL);
xfs_trans_ijoin(tp, ip);

- error = xfs_itruncate_finish(&tp, ip,
- ip->i_size,
- XFS_DATA_FORK,
- 0);
- /*
- * If we get an error at this point we
- * simply don't bother truncating the file.
- */
+ error = xfs_itruncate_data(&tp, ip, ip->i_size);
if (error) {
+ /*
+ * If we get an error at this point we simply don't
+ * bother truncating the file.
+ */
xfs_trans_cancel(tp,
(XFS_TRANS_RELEASE_LOG_RES |
XFS_TRANS_ABORT));
@@ -665,16 +662,7 @@ xfs_inactive(
xfs_ilock(ip, XFS_ILOCK_EXCL);
xfs_trans_ijoin(tp, ip);

- /*
- * normally, we have to run xfs_itruncate_finish sync.
- * But if filesystem is wsync and we're in the inactive
- * path, then we know that nlink == 0, and that the
- * xaction that made nlink == 0 is permanently committed
- * since xfs_remove runs as a synchronous transaction.
- */
- error = xfs_itruncate_finish(&tp, ip, 0, XFS_DATA_FORK,
- (!(mp->m_flags & XFS_MOUNT_WSYNC) ? 1 : 0));
-
+ error = xfs_itruncate_data(&tp, ip, 0);
if (error) {
xfs_trans_cancel(tp,
XFS_TRANS_RELEASE_LOG_RES | XFS_TRANS_ABORT);
Index: xfs/fs/xfs/linux-2.6/xfs_trace.h
===================================================================
--- xfs.orig/fs/xfs/linux-2.6/xfs_trace.h 2011-07-05 13:36:54.592679793 +0200
+++ xfs/fs/xfs/linux-2.6/xfs_trace.h 2011-07-05 13:36:57.119332771 +0200
@@ -1059,8 +1059,8 @@ DECLARE_EVENT_CLASS(xfs_itrunc_class,
DEFINE_EVENT(xfs_itrunc_class, name, \
TP_PROTO(struct xfs_inode *ip, xfs_fsize_t new_size), \
TP_ARGS(ip, new_size))
-DEFINE_ITRUNC_EVENT(xfs_itruncate_finish_start);
-DEFINE_ITRUNC_EVENT(xfs_itruncate_finish_end);
+DEFINE_ITRUNC_EVENT(xfs_itruncate_data_start);
+DEFINE_ITRUNC_EVENT(xfs_itruncate_data_end);

TRACE_EVENT(xfs_pagecache_inval,
TP_PROTO(struct xfs_inode *ip, xfs_off_t start, xfs_off_t finish),