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fs/pipe.c: preserve alloc_file() error code 

If sys_pipe() was unable to allocate a 'struct file', it always failed
with ENFILE, which means "The number of simultaneously open files in the
system would exceed a system-imposed limit." However, alloc_file()
actually returns an ERR_PTR value and might fail with other error codes.
Currently, in addition to ENFILE, it can fail with ENOMEM, potentially
when there are few open files in the system.  Update sys_pipe() to
preserve this error code.

In a prior submission of a similar patch (1) some concern was raised
about introducing a new error code for sys_pipe().  However, for most
system calls, programs cannot assume that new error codes will never be
introduced.  In addition, ENOMEM was, in fact, already a possible error
code for sys_pipe(), in the case where the file descriptor table could
not be expanded due to insufficient memory.

	(1) http://comments.gmane.org/gmane.linux.kernel/1357942

Signed-off-by: Eric Biggers <ebiggers3@gmail.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Eric Biggers 2015-10-17 16:26:08 -05:00 committed by Al Viro
parent b582ef5c53
commit e9bb1f9b12
1 changed files with 6 additions and 3 deletions
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9
fs/pipe.c
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@ -693,17 +693,20 @@ int create_pipe_files(struct file **res, int flags)
d_instantiate(path.dentry, inode);
err = -ENFILE;
f = alloc_file(&path, FMODE_WRITE, &pipefifo_fops);
if (IS_ERR(f))
if (IS_ERR(f)) {
err = PTR_ERR(f);
goto err_dentry;
}
f->f_flags = O_WRONLY | (flags & (O_NONBLOCK | O_DIRECT));
f->private_data = inode->i_pipe;
res[0] = alloc_file(&path, FMODE_READ, &pipefifo_fops);
if (IS_ERR(res[0]))
if (IS_ERR(res[0])) {
err = PTR_ERR(res[0]);
goto err_file;
}
path_get(&path);
res[0]->private_data = inode->i_pipe;