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, 2 insertions, 2 deletions

diff --git a/fs/pipe.c b/fs/pipe.c
index 39baf6c..64a494c 100644
--- a/fs/pipe.c
+++ b/fs/pipe.c
@@ -1037,13 +1037,13 @@ int create_pipe_files(struct file **res, int flags)
 
 	err = -ENFILE;
 	f = alloc_file(&path, FMODE_WRITE, &write_pipefifo_fops);
-	if (!f)
+	if (IS_ERR(f))
 		goto err_dentry;
 
 	f->f_flags = O_WRONLY | (flags & (O_NONBLOCK | O_DIRECT));
 
 	res[0] = alloc_file(&path, FMODE_READ, &read_pipefifo_fops);
-	if (!res[0])
+	if (IS_ERR(res[0]))
 		goto err_file;
 
 	path_get(&path);