From: NeilBrown <neilb@suse.de>
Date: Sun, 10 Oct 2010 23:47:33 +0000 (+1100)
Subject: While truncating, hold ref on superblock as well as inode.
X-Git-Url: http://git.neil.brown.name/?a=commitdiff_plain;h=6c2ff96dfb857fab2dde256afc383c8694a375ac;p=LaFS.git

While truncating, hold ref on superblock as well as inode.


An unmount of a subsect filesystem could happen while still truncating
a file on the filesystem.  So hold a ref to the superblock so that it
doesn't go away.
When deleting, we cannot grab the inode, so we need to modify
lafs_iput_fs to not do an iput in that case.

Signed-off-by: NeilBrown <neilb@suse.de>
---

diff --git a/inode.c b/inode.c
index 1c65172..acc9261 100644
--- a/inode.c
+++ b/inode.c
@@ -705,9 +705,10 @@ void lafs_delete_inode(struct inode *ino)
 	i_size_write(ino, 0);
 	truncate_inode_pages(&ino->i_data, 0);
 	LAFSI(ino)->trunc_next = 0;
+	set_bit(I_Deleting, &LAFSI(ino)->iflags);
 	set_bit(I_Trunc, &LAFSI(ino)->iflags);
+	lafs_igrab_fs(ino);
 
-	set_bit(I_Deleting, &LAFSI(ino)->iflags);
 	if (!IS_ERR(b)) {
 		set_bit(B_Claimed, &b->b.flags);
 		lafs_add_orphan(fs, b);
@@ -851,8 +852,7 @@ int lafs_inode_handle_orphan(struct datablock *b)
 			/* must be finished */
 			LAFS_BUG(test_bit(B_Dirty, &ib->b.flags), &ib->b);
 			clear_bit(I_Trunc, &LAFSI(ino)->iflags);
-			if (!test_bit(I_Deleting, &LAFSI(ino)->iflags))
-				iput(ino);
+			lafs_iput_fs(ino);
 			wake_up(&fs->trunc_wait);
 			err = -ERESTARTSYS;
 			goto out2;
@@ -894,8 +894,7 @@ int lafs_inode_handle_orphan(struct datablock *b)
 			/* Must be all done */
 			spin_unlock(&ib->b.inode->i_data.private_lock);
 			clear_bit(I_Trunc, &LAFSI(ino)->iflags);
-			if (!test_bit(I_Deleting, &LAFSI(ino)->iflags))
-				iput(ino);
+			lafs_iput_fs(ino);
 			wake_up(&fs->trunc_wait);
 			err = -ERESTARTSYS;
 			goto out2;
@@ -966,8 +965,7 @@ int lafs_inode_handle_orphan(struct datablock *b)
 	if (LAFSI(ino)->depth == 0) {
 		/* Nothing to truncate */
 		clear_bit(I_Trunc, &LAFSI(ino)->iflags);
-		if (!test_bit(I_Deleting, &LAFSI(ino)->iflags))
-			iput(ino);
+		lafs_iput_fs(ino);
 		if (test_bit(B_Pinned, &ib->b.flags))
 			/* Need to move the dirtiness which keeps this
 			 * pinned to the data block.
@@ -1748,7 +1746,7 @@ void lafs_truncate(struct inode *ino)
 	lafs_make_orphan(fs, db);
 
 	if (!test_and_set_bit(I_Trunc, &LAFSI(ino)->iflags))
-		igrab(ino);
+		lafs_igrab_fs(ino);
 	if (trunc_block == 0)
 		LAFSI(ino)->trunc_gen++;
 	LAFSI(ino)->trunc_next = trunc_block;
diff --git a/lafs.h b/lafs.h
index c6c0bb2..42198fa 100644
--- a/lafs.h
+++ b/lafs.h
@@ -156,13 +156,16 @@ int lafs_inode_handle_orphan(struct datablock *b);
 static inline void lafs_iput_fs(struct inode *ino)
 {
 	struct super_block *sb = ino->i_sb;
-	iput(ino);
+	if (!test_bit(I_Deleting, &LAFSI(ino)->iflags))
+		iput(ino);
 	deactivate_super(sb);
 }
 
 static inline void lafs_igrab_fs(struct inode *ino)
 {
-	igrab(ino);
+	if (igrab(ino) == NULL &&	
+	    !test_bit(I_Deleting, &LAFSI(ino)->iflags))
+		BUG();
 	atomic_inc(&ino->i_sb->s_active);
 }