fs: Preserve error code in get_empty_filp(), part 2

Allocating a file structure in function get_empty_filp() might fail because
of several reasons:
 - not enough memory for file structures
 - operation is not allowed
 - user is over its limit

Currently the function returns NULL in all cases and we loose the exact
reason of the error. All callers of get_empty_filp() assume that the function
can fail with ENFILE only.

Return error through pointer. Change all callers to preserve this error code.

[AV: cleaned up a bit, carved the get_empty_filp() part out into a separate commit
(things remaining here deal with alloc_file()), removed pipe(2) behaviour change]

Signed-off-by: Anatol Pomozov <anatol.pomozov@gmail.com>
Reviewed-by: "Theodore Ts'o" <tytso@mit.edu>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

1 files changed, 3 insertions, 5 deletions

diff --git a/fs/anon_inodes.c b/fs/anon_inodes.c
index 28d39fb..a14eb0c 100644
--- a/fs/anon_inodes.c
+++ b/fs/anon_inodes.c
@@ -131,7 +131,6 @@ struct file *anon_inode_getfile(const char *name,
 	struct qstr this;
 	struct path path;
 	struct file *file;
-	int error;
 
 	if (IS_ERR(anon_inode_inode))
 		return ERR_PTR(-ENODEV);
@@ -143,7 +142,7 @@ struct file *anon_inode_getfile(const char *name,
 	 * Link the inode to a directory entry by creating a unique name
 	 * using the inode sequence number.
 	 */
-	error = -ENOMEM;
+	file = ERR_PTR(-ENOMEM);
 	this.name = name;
 	this.len = strlen(name);
 	this.hash = 0;
@@ -160,9 +159,8 @@ struct file *anon_inode_getfile(const char *name,
 
 	d_instantiate(path.dentry, anon_inode_inode);
 
-	error = -ENFILE;
 	file = alloc_file(&path, OPEN_FMODE(flags), fops);
-	if (!file)
+	if (IS_ERR(file))
 		goto err_dput;
 	file->f_mapping = anon_inode_inode->i_mapping;
 
@@ -177,7 +175,7 @@ err_dput:
 	path_put(&path);
 err_module:
 	module_put(fops->owner);
-	return ERR_PTR(error);
+	return file;
 }
 EXPORT_SYMBOL_GPL(anon_inode_getfile);