xfs: merge fsync and O_SYNC handling

The guarantees for O_SYNC are exactly the same as the ones we need to
make for an fsync call (and given that Linux O_SYNC is O_DSYNC the
equivalent is fdadatasync, but we treat both the same in XFS), except
with a range data writeout.  Jan Kara has started unifying these two
path for filesystems using the generic helpers, and I've started to
look at XFS.

The actual transaction commited by xfs_fsync and xfs_write_sync_logforce
has a different transaction number, but actually is exactly the same.
We'll only use the fsync transaction going forward.  One major difference
is that xfs_write_sync_logforce never issues a cache flush unless we
commit a transaction causing that as a side-effect, which is an obvious
bug in the O_SYNC handling.  Second all the locking and i_update_size
vs i_update_core changes from 978b7237123d007b9fa983af6e0e2fa8f97f9934
never made it to xfs_write_sync_logforce, so we add them back.

To make xfs_fsync easily usable from the O_SYNC path, the filemap_fdatawait
call is moved up to xfs_file_fsync, so that we don't wait on the whole
file after we already waited for our portion in xfs_write.

We'll also use a plain call to filemap_write_and_wait_range instead
of the previous sync_page_rang which did it in two steps including
an half-hearted inode write out that doesn't help us.

Once we're done with this also remove the now useless i_update_size
tracking.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Felix Blyakher <felixb@sgi.com>
Signed-off-by: Felix Blyakher <felixb@sgi.com>

10 files changed, 23 insertions, 112 deletions

diff --git a/fs/xfs/linux-2.6/xfs_aops.c b/fs/xfs/linux-2.6/xfs_aops.c
index aecf2519db7..d5e5559e31d 100644
--- a/fs/xfs/linux-2.6/xfs_aops.c
+++ b/fs/xfs/linux-2.6/xfs_aops.c
@@ -216,7 +216,6 @@ xfs_setfilesize(
         if (ip->i_d.di_size < isize) {
                 ip->i_d.di_size = isize;
                 ip->i_update_core = 1;
-                ip->i_update_size = 1;
                 xfs_mark_inode_dirty_sync(ip);
         }
 
diff --git a/fs/xfs/linux-2.6/xfs_file.c b/fs/xfs/linux-2.6/xfs_file.c
index 0542fd50764..988d8f87bc0 100644
--- a/fs/xfs/linux-2.6/xfs_file.c
+++ b/fs/xfs/linux-2.6/xfs_file.c
@@ -172,12 +172,21 @@ xfs_file_release(
  */
 STATIC int
 xfs_file_fsync(
-        struct file     *filp,
-        struct dentry   *dentry,
-        int             datasync)
+        struct file             *file,
+        struct dentry           *dentry,
+        int                     datasync)
 {
-        xfs_iflags_clear(XFS_I(dentry->d_inode), XFS_ITRUNCATED);
-        return -xfs_fsync(XFS_I(dentry->d_inode));
+        struct inode            *inode = dentry->d_inode;
+        struct xfs_inode        *ip = XFS_I(inode);
+        int                     error;
+
+        /* capture size updates in I/O completion before writing the inode. */
+        error = filemap_fdatawait(inode->i_mapping);
+        if (error)
+                return error;
+
+        xfs_iflags_clear(ip, XFS_ITRUNCATED);
+        return -xfs_fsync(ip);
 }
 
 STATIC int
diff --git a/fs/xfs/linux-2.6/xfs_lrw.c b/fs/xfs/linux-2.6/xfs_lrw.c
index 7078974a6ee..49e4a6aea73 100644
--- a/fs/xfs/linux-2.6/xfs_lrw.c
+++ b/fs/xfs/linux-2.6/xfs_lrw.c
@@ -812,18 +812,21 @@ write_retry:
 
         /* Handle various SYNC-type writes */
         if ((file->f_flags & O_SYNC) || IS_SYNC(inode)) {
+                loff_t end = pos + ret - 1;
                 int error2;
 
                 xfs_iunlock(xip, iolock);
                 if (need_i_mutex)
                         mutex_unlock(&inode->i_mutex);
-                error2 = sync_page_range(inode, mapping, pos, ret);
+
+                error2 = filemap_write_and_wait_range(mapping, pos, end);
                 if (!error)
                         error = error2;
                 if (need_i_mutex)
                         mutex_lock(&inode->i_mutex);
                 xfs_ilock(xip, iolock);
-                error2 = xfs_write_sync_logforce(mp, xip);
+
+                error2 = xfs_fsync(xip);
                 if (!error)
                         error = error2;
         }
diff --git a/fs/xfs/xfs_iget.c b/fs/xfs/xfs_iget.c
index ecbf8b4d2e2..3323826274b 100644
--- a/fs/xfs/xfs_iget.c
+++ b/fs/xfs/xfs_iget.c
@@ -82,7 +82,6 @@ xfs_inode_alloc(
         memset(&ip->i_df, 0, sizeof(xfs_ifork_t));
         ip->i_flags = 0;
         ip->i_update_core = 0;
-        ip->i_update_size = 0;
         ip->i_delayed_blks = 0;
         memset(&ip->i_d, 0, sizeof(xfs_icdinode_t));
         ip->i_size = 0;
diff --git a/fs/xfs/xfs_inode.h b/fs/xfs/xfs_inode.h
index 00e8505bde2..ed566c248ae 100644
--- a/fs/xfs/xfs_inode.h
+++ b/fs/xfs/xfs_inode.h
@@ -261,7 +261,6 @@ typedef struct xfs_inode {
         /* Miscellaneous state. */
         unsigned short          i_flags;        /* see defined flags below */
         unsigned char           i_update_core;  /* timestamps/size is dirty */
-        unsigned char           i_update_size;  /* di_size field is dirty */
         unsigned int            i_delayed_blks; /* count of delay alloc blks */
 
         xfs_icdinode_t          i_d;            /* most of ondisk inode */
diff --git a/fs/xfs/xfs_inode_item.c b/fs/xfs/xfs_inode_item.c
index 977c4aec587..2e69412195e 100644
--- a/fs/xfs/xfs_inode_item.c
+++ b/fs/xfs/xfs_inode_item.c
@@ -263,14 +263,6 @@ xfs_inode_item_format(
         }
 
         /*
-         * We don't have to worry about re-ordering here because
-         * the update_size field is protected by the inode lock
-         * and we have that held in exclusive mode.
-         */
-        if (ip->i_update_size)
-                ip->i_update_size = 0;
-
-        /*
          * Make sure to get the latest atime from the Linux inode.
          */
         xfs_synchronize_atime(ip);
diff --git a/fs/xfs/xfs_rw.c b/fs/xfs/xfs_rw.c
index fea68615ed2..3f816ad7ff1 100644
--- a/fs/xfs/xfs_rw.c
+++ b/fs/xfs/xfs_rw.c
@@ -88,90 +88,6 @@ xfs_write_clear_setuid(
 }
 
 /*
- * Handle logging requirements of various synchronous types of write.
- */
-int
-xfs_write_sync_logforce(
-        xfs_mount_t     *mp,
-        xfs_inode_t     *ip)
-{
-        int             error = 0;
-
-        /*
-         * If we're treating this as O_DSYNC and we have not updated the
-         * size, force the log.
-         */
-        if (!(mp->m_flags & XFS_MOUNT_OSYNCISOSYNC) &&
-            !(ip->i_update_size)) {
-                xfs_inode_log_item_t    *iip = ip->i_itemp;
-
-                /*
-                 * If an allocation transaction occurred
-                 * without extending the size, then we have to force
-                 * the log up the proper point to ensure that the
-                 * allocation is permanent.  We can't count on
-                 * the fact that buffered writes lock out direct I/O
-                 * writes - the direct I/O write could have extended
-                 * the size nontransactionally, then finished before
-                 * we started.  xfs_write_file will think that the file
-                 * didn't grow but the update isn't safe unless the
-                 * size change is logged.
-                 *
-                 * Force the log if we've committed a transaction
-                 * against the inode or if someone else has and
-                 * the commit record hasn't gone to disk (e.g.
-                 * the inode is pinned).  This guarantees that
-                 * all changes affecting the inode are permanent
-                 * when we return.
-                 */
-                if (iip && iip->ili_last_lsn) {
-                        error = _xfs_log_force(mp, iip->ili_last_lsn,
-                                        XFS_LOG_FORCE | XFS_LOG_SYNC, NULL);
-                } else if (xfs_ipincount(ip) > 0) {
-                        error = _xfs_log_force(mp, (xfs_lsn_t)0,
-                                        XFS_LOG_FORCE | XFS_LOG_SYNC, NULL);
-                }
-
-        } else {
-                xfs_trans_t     *tp;
-
-                /*
-                 * O_SYNC or O_DSYNC _with_ a size update are handled
-                 * the same way.
-                 *
-                 * If the write was synchronous then we need to make
-                 * sure that the inode modification time is permanent.
-                 * We'll have updated the timestamp above, so here
-                 * we use a synchronous transaction to log the inode.
-                 * It's not fast, but it's necessary.
-                 *
-                 * If this a dsync write and the size got changed
-                 * non-transactionally, then we need to ensure that
-                 * the size change gets logged in a synchronous
-                 * transaction.
-                 */
-                tp = xfs_trans_alloc(mp, XFS_TRANS_WRITE_SYNC);
-                if ((error = xfs_trans_reserve(tp, 0,
-                                                XFS_SWRITE_LOG_RES(mp),
-                                                0, 0, 0))) {
-                        /* Transaction reserve failed */
-                        xfs_trans_cancel(tp, 0);
-                } else {
-                        /* Transaction reserve successful */
-                        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);
-                        xfs_trans_set_sync(tp);
-                        error = xfs_trans_commit(tp, 0);
-                        xfs_iunlock(ip, XFS_ILOCK_EXCL);
-                }
-        }
-
-        return error;
-}
-
-/*
  * 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
diff --git a/fs/xfs/xfs_rw.h b/fs/xfs/xfs_rw.h
index ae65f0df87d..f5e4874c37d 100644
--- a/fs/xfs/xfs_rw.h
+++ b/fs/xfs/xfs_rw.h
@@ -68,7 +68,6 @@ xfs_get_extsz_hint(
  * Prototypes for functions in xfs_rw.c.
  */
 extern int xfs_write_clear_setuid(struct xfs_inode *ip);
-extern int xfs_write_sync_logforce(struct xfs_mount *mp, struct xfs_inode *ip);
 extern int xfs_bwrite(struct xfs_mount *mp, struct xfs_buf *bp);
 extern int xfs_bioerror(struct xfs_buf *bp);
 extern int xfs_bioerror_relse(struct xfs_buf *bp);
diff --git a/fs/xfs/xfs_trans.h b/fs/xfs/xfs_trans.h
index 775249a54f6..ed47fc77759 100644
--- a/fs/xfs/xfs_trans.h
+++ b/fs/xfs/xfs_trans.h
@@ -68,7 +68,7 @@ typedef struct xfs_trans_header {
 #define XFS_TRANS_GROWFS                14
 #define XFS_TRANS_STRAT_WRITE           15
 #define XFS_TRANS_DIOSTRAT              16
-#define XFS_TRANS_WRITE_SYNC            17
+/* 17 was XFS_TRANS_WRITE_SYNC */
 #define XFS_TRANS_WRITEID               18
 #define XFS_TRANS_ADDAFORK              19
 #define XFS_TRANS_ATTRINVAL             20
diff --git a/fs/xfs/xfs_vnodeops.c b/fs/xfs/xfs_vnodeops.c
index ceecafd1f9c..03d3100559a 100644
--- a/fs/xfs/xfs_vnodeops.c
+++ b/fs/xfs/xfs_vnodeops.c
@@ -611,7 +611,7 @@ xfs_fsync(
         xfs_inode_t     *ip)
 {
         xfs_trans_t     *tp;
-        int             error;
+        int             error = 0;
         int             log_flushed = 0, changed = 1;
 
         xfs_itrace_entry(ip);
@@ -619,14 +619,9 @@ xfs_fsync(
         if (XFS_FORCED_SHUTDOWN(ip->i_mount))
                 return XFS_ERROR(EIO);
 
-        /* capture size updates in I/O completion before writing the inode. */
-        error = xfs_wait_on_pages(ip, 0, -1);
-        if (error)
-                return XFS_ERROR(error);
-
         /*
          * We always need to make sure that the required inode state is safe on
-         * disk.  The vnode might be clean but we still might need to force the
+         * disk.  The inode might be clean but we still might need to force the
          * log because of committed transactions that haven't hit the disk yet.
          * Likewise, there could be unflushed non-transactional changes to the
          * inode core that have to go to disk and this requires us to issue
@@ -638,7 +633,7 @@ xfs_fsync(
          */
         xfs_ilock(ip, XFS_ILOCK_SHARED);
 
-        if (!(ip->i_update_size || ip->i_update_core)) {
+        if (!ip->i_update_core) {
                 /*
                  * Timestamps/size haven't changed since last inode flush or
                  * inode transaction commit.  That means either nothing got