xfs: implement ->dirty_inode to fix timestamp handling

This is picking up on Felix's repost of Dave's patch to implement a
.dirty_inode method.  We really need this notification because
the VFS keeps writing directly into the inode structure instead
of going through methods to update this state.  In addition to
the long-known atime issue we now also have a caller in VM code
that updates c/mtime that way for shared writeable mmaps.  And
I found another one that no one has noticed in practice in the FIFO
code.

So implement ->dirty_inode to set i_update_core whenever the
inode gets externally dirtied, and switch the c/mtime handling to
the same scheme we already use for atime (always picking up
the value from the Linux inode).

Note that this patch also removes the xfs_synchronize_atime call
in xfs_reclaim it was superflous as we already synchronize the time
when writing the inode via the log (xfs_inode_item_format) or the
normal buffers (xfs_iflush_int).

In addition also remove the I_CLEAR check before copying the Linux
timestamps - now that we always have the Linux inode available
we can always use the timestamps in it.

Also switch to just using file_update_time for regular reads/writes -
that will get us all optimization done to it for free and make
sure we notice early when it breaks.

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

4 files changed, 39 insertions, 28 deletions

diff --git a/fs/xfs/linux-2.6/xfs_aops.c b/fs/xfs/linux-2.6/xfs_aops.c
index d5e5559e31db3..40d2226060d17 100644
--- a/fs/xfs/linux-2.6/xfs_aops.c
+++ b/fs/xfs/linux-2.6/xfs_aops.c
@@ -215,7 +215,6 @@ xfs_setfilesize(
 
 	if (ip->i_d.di_size < isize) {
 		ip->i_d.di_size = isize;
-		ip->i_update_core = 1;
 		xfs_mark_inode_dirty_sync(ip);
 	}
 
diff --git a/fs/xfs/linux-2.6/xfs_iops.c b/fs/xfs/linux-2.6/xfs_iops.c
index 626b474b2cdde..cdf7114d41fc3 100644
--- a/fs/xfs/linux-2.6/xfs_iops.c
+++ b/fs/xfs/linux-2.6/xfs_iops.c
@@ -57,19 +57,22 @@
 #include <linux/fiemap.h>
 
 /*
- * Bring the atime in the XFS inode uptodate.
- * Used before logging the inode to disk or when the Linux inode goes away.
+ * Bring the timestamps in the XFS inode uptodate.
+ *
+ * Used before writing the inode to disk.
  */
 void
-xfs_synchronize_atime(
+xfs_synchronize_times(
 	xfs_inode_t	*ip)
 {
 	struct inode	*inode = VFS_I(ip);
 
-	if (!(inode->i_state & I_CLEAR)) {
-		ip->i_d.di_atime.t_sec = (__int32_t)inode->i_atime.tv_sec;
-		ip->i_d.di_atime.t_nsec = (__int32_t)inode->i_atime.tv_nsec;
-	}
+	ip->i_d.di_atime.t_sec = (__int32_t)inode->i_atime.tv_sec;
+	ip->i_d.di_atime.t_nsec = (__int32_t)inode->i_atime.tv_nsec;
+	ip->i_d.di_ctime.t_sec = (__int32_t)inode->i_ctime.tv_sec;
+	ip->i_d.di_ctime.t_nsec = (__int32_t)inode->i_ctime.tv_nsec;
+	ip->i_d.di_mtime.t_sec = (__int32_t)inode->i_mtime.tv_sec;
+	ip->i_d.di_mtime.t_nsec = (__int32_t)inode->i_mtime.tv_nsec;
 }
 
 /*
@@ -106,32 +109,20 @@ xfs_ichgtime(
 	if ((flags & XFS_ICHGTIME_MOD) &&
 	    !timespec_equal(&inode->i_mtime, &tv)) {
 		inode->i_mtime = tv;
-		ip->i_d.di_mtime.t_sec = (__int32_t)tv.tv_sec;
-		ip->i_d.di_mtime.t_nsec = (__int32_t)tv.tv_nsec;
 		sync_it = 1;
 	}
 	if ((flags & XFS_ICHGTIME_CHG) &&
 	    !timespec_equal(&inode->i_ctime, &tv)) {
 		inode->i_ctime = tv;
-		ip->i_d.di_ctime.t_sec = (__int32_t)tv.tv_sec;
-		ip->i_d.di_ctime.t_nsec = (__int32_t)tv.tv_nsec;
 		sync_it = 1;
 	}
 
 	/*
-	 * We update the i_update_core field _after_ changing
-	 * the timestamps in order to coordinate properly with
-	 * xfs_iflush() so that we don't lose timestamp updates.
-	 * This keeps us from having to hold the inode lock
-	 * while doing this.  We use the SYNCHRONIZE macro to
-	 * ensure that the compiler does not reorder the update
-	 * of i_update_core above the timestamp updates above.
+	 * Update complete - now make sure everyone knows that the inode
+	 * is dirty.
 	 */
-	if (sync_it) {
-		SYNCHRONIZE();
-		ip->i_update_core = 1;
+	if (sync_it)
 		xfs_mark_inode_dirty_sync(ip);
-	}
 }
 
 /*
@@ -514,10 +505,8 @@ xfs_vn_getattr(
 	stat->gid = ip->i_d.di_gid;
 	stat->ino = ip->i_ino;
 	stat->atime = inode->i_atime;
-	stat->mtime.tv_sec = ip->i_d.di_mtime.t_sec;
-	stat->mtime.tv_nsec = ip->i_d.di_mtime.t_nsec;
-	stat->ctime.tv_sec = ip->i_d.di_ctime.t_sec;
-	stat->ctime.tv_nsec = ip->i_d.di_ctime.t_nsec;
+	stat->mtime = inode->i_mtime;
+	stat->ctime = inode->i_ctime;
 	stat->blocks =
 		XFS_FSB_TO_BB(mp, ip->i_d.di_nblocks + ip->i_delayed_blks);
 
diff --git a/fs/xfs/linux-2.6/xfs_lrw.c b/fs/xfs/linux-2.6/xfs_lrw.c
index 49e4a6aea73c3..072050f8d3463 100644
--- a/fs/xfs/linux-2.6/xfs_lrw.c
+++ b/fs/xfs/linux-2.6/xfs_lrw.c
@@ -667,7 +667,7 @@ start:
 		xip->i_new_size = new_size;
 
 	if (likely(!(ioflags & IO_INVIS)))
-		xfs_ichgtime(xip, XFS_ICHGTIME_MOD | XFS_ICHGTIME_CHG);
+		file_update_time(file);
 
 	/*
 	 * If the offset is beyond the size of the file, we have a couple
diff --git a/fs/xfs/linux-2.6/xfs_super.c b/fs/xfs/linux-2.6/xfs_super.c
index 5d7c60ac77b49..1ea65b6e5ab66 100644
--- a/fs/xfs/linux-2.6/xfs_super.c
+++ b/fs/xfs/linux-2.6/xfs_super.c
@@ -977,6 +977,28 @@ xfs_fs_inode_init_once(
 }
 
 /*
+ * Dirty the XFS inode when mark_inode_dirty_sync() is called so that
+ * we catch unlogged VFS level updates to the inode. Care must be taken
+ * here - the transaction code calls mark_inode_dirty_sync() to mark the
+ * VFS inode dirty in a transaction and clears the i_update_core field;
+ * it must clear the field after calling mark_inode_dirty_sync() to
+ * correctly indicate that the dirty state has been propagated into the
+ * inode log item.
+ *
+ * We need the barrier() to maintain correct ordering between unlogged
+ * updates and the transaction commit code that clears the i_update_core
+ * field. This requires all updates to be completed before marking the
+ * inode dirty.
+ */
+STATIC void
+xfs_fs_dirty_inode(
+	struct inode	*inode)
+{
+	barrier();
+	XFS_I(inode)->i_update_core = 1;
+}
+
+/*
  * Attempt to flush the inode, this will actually fail
  * if the inode is pinned, but we dirty the inode again
  * at the point when it is unpinned after a log write,
@@ -1539,6 +1561,7 @@ xfs_fs_get_sb(
 static struct super_operations xfs_super_operations = {
 	.alloc_inode		= xfs_fs_alloc_inode,
 	.destroy_inode		= xfs_fs_destroy_inode,
+	.dirty_inode		= xfs_fs_dirty_inode,
 	.write_inode		= xfs_fs_write_inode,
 	.clear_inode		= xfs_fs_clear_inode,
 	.put_super		= xfs_fs_put_super,