Fix reiserfs_file_release()

a) count file openers correctly; i_count use was completely wrong
b) use new mutex for exclusion between final close/open/truncate,
to protect tailpacking logics.  i_mutex use was wrong and resulted
in deadlocks.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

fs/reiserfs/file.c

@@ -38,20 +38,24 @@ static int reiserfs_file_release(struct inode *inode, struct file *filp)
 
 	BUG_ON(!S_ISREG(inode->i_mode));
 
+        if (atomic_add_unless(&REISERFS_I(inode)->openers, -1, 1))
+		return 0;
+
+	mutex_lock(&(REISERFS_I(inode)->tailpack));
+
+        if (!atomic_dec_and_test(&REISERFS_I(inode)->openers)) {
+		mutex_unlock(&(REISERFS_I(inode)->tailpack));
+		return 0;
+	}
+
 	/* fast out for when nothing needs to be done */
-	if ((atomic_read(&inode->i_count) > 1 ||
-	     !(REISERFS_I(inode)->i_flags & i_pack_on_close_mask) ||
+	if ((!(REISERFS_I(inode)->i_flags & i_pack_on_close_mask) ||
 	     !tail_has_to_be_packed(inode)) &&
 	    REISERFS_I(inode)->i_prealloc_count <= 0) {
+		mutex_unlock(&(REISERFS_I(inode)->tailpack));
 		return 0;
 	}
 
-	mutex_lock(&inode->i_mutex);
-
-	mutex_lock(&(REISERFS_I(inode)->i_mmap));
-	if (REISERFS_I(inode)->i_flags & i_ever_mapped)
-		REISERFS_I(inode)->i_flags &= ~i_pack_on_close_mask;
-
 	reiserfs_write_lock(inode->i_sb);
 	/* freeing preallocation only involves relogging blocks that
 	 * are already in the current transaction.  preallocation gets
@@ -94,9 +98,10 @@ static int reiserfs_file_release(struct inode *inode, struct file *filp)
 	if (!err)
 		err = jbegin_failure;
 
-	if (!err && atomic_read(&inode->i_count) <= 1 &&
+	if (!err &&
 	    (REISERFS_I(inode)->i_flags & i_pack_on_close_mask) &&
 	    tail_has_to_be_packed(inode)) {
+
 		/* if regular file is released by last holder and it has been
 		   appended (we append by unformatted node only) or its direct
 		   item(s) had to be converted, then it may have to be
@@ -104,27 +109,28 @@ static int reiserfs_file_release(struct inode *inode, struct file *filp)
 		err = reiserfs_truncate_file(inode, 0);
 	}
       out:
-	mutex_unlock(&(REISERFS_I(inode)->i_mmap));
-	mutex_unlock(&inode->i_mutex);
 	reiserfs_write_unlock(inode->i_sb);
+	mutex_unlock(&(REISERFS_I(inode)->tailpack));
 	return err;
 }
 
-static int reiserfs_file_mmap(struct file *file, struct vm_area_struct *vma)
+static int reiserfs_file_open(struct inode *inode, struct file *file)
 {
-	struct inode *inode;
-
-	inode = file->f_path.dentry->d_inode;
-	mutex_lock(&(REISERFS_I(inode)->i_mmap));
-	REISERFS_I(inode)->i_flags |= i_ever_mapped;
-	mutex_unlock(&(REISERFS_I(inode)->i_mmap));
-
-	return generic_file_mmap(file, vma);
+	int err = dquot_file_open(inode, file);
+        if (!atomic_inc_not_zero(&REISERFS_I(inode)->openers)) {
+		/* somebody might be tailpacking on final close; wait for it */
+		mutex_lock(&(REISERFS_I(inode)->tailpack));
+		atomic_inc(&REISERFS_I(inode)->openers);
+		mutex_unlock(&(REISERFS_I(inode)->tailpack));
+	}
+	return err;
 }
 
 static void reiserfs_vfs_truncate_file(struct inode *inode)
 {
+	mutex_lock(&(REISERFS_I(inode)->tailpack));
 	reiserfs_truncate_file(inode, 1);
+	mutex_unlock(&(REISERFS_I(inode)->tailpack));
 }
 
 /* Sync a reiserfs file. */
@@ -288,8 +294,8 @@ const struct file_operations reiserfs_file_operations = {
 #ifdef CONFIG_COMPAT
 	.compat_ioctl = reiserfs_compat_ioctl,
 #endif
-	.mmap = reiserfs_file_mmap,
-	.open = dquot_file_open,
+	.mmap = generic_file_mmap,
+	.open = reiserfs_file_open,
 	.release = reiserfs_file_release,
 	.fsync = reiserfs_sync_file,
 	.aio_read = generic_file_aio_read,

fs/reiserfs/inode.c

@@ -1138,7 +1138,6 @@ static void init_inode(struct inode *inode, struct treepath *path)
 	REISERFS_I(inode)->i_prealloc_count = 0;
 	REISERFS_I(inode)->i_trans_id = 0;
 	REISERFS_I(inode)->i_jl = NULL;
-	mutex_init(&(REISERFS_I(inode)->i_mmap));
 	reiserfs_init_xattr_rwsem(inode);
 
 	if (stat_data_v1(ih)) {
@@ -1841,7 +1840,6 @@ int reiserfs_new_inode(struct reiserfs_transaction_handle *th,
 	REISERFS_I(inode)->i_attrs =
 	    REISERFS_I(dir)->i_attrs & REISERFS_INHERIT_MASK;
 	sd_attrs_to_i_attrs(REISERFS_I(inode)->i_attrs, inode);
-	mutex_init(&(REISERFS_I(inode)->i_mmap));
 	reiserfs_init_xattr_rwsem(inode);
 
 	/* key to search for correct place for new stat data */

fs/reiserfs/super.c

@@ -525,6 +525,8 @@ static struct inode *reiserfs_alloc_inode(struct super_block *sb)
 	    kmem_cache_alloc(reiserfs_inode_cachep, GFP_KERNEL);
 	if (!ei)
 		return NULL;
+	atomic_set(&ei->openers, 0);
+	mutex_init(&ei->tailpack);
 	return &ei->vfs_inode;
 }
 

include/linux/reiserfs_fs_i.h

@@ -25,7 +25,6 @@ typedef enum {
 	i_link_saved_truncate_mask = 0x0020,
 	i_has_xattr_dir = 0x0040,
 	i_data_log = 0x0080,
-	i_ever_mapped = 0x0100
 } reiserfs_inode_flags;
 
 struct reiserfs_inode_info {
@@ -53,7 +52,8 @@ struct reiserfs_inode_info {
 	 ** flushed */
 	unsigned int i_trans_id;
 	struct reiserfs_journal_list *i_jl;
-	struct mutex i_mmap;
+	atomic_t openers;
+	struct mutex tailpack;
 #ifdef CONFIG_REISERFS_FS_XATTR
 	struct rw_semaphore i_xattr_sem;
 #endif