proc mountinfo: make splice available again

Since commit 36e2c7421f02 ("fs: don't allow splice read/write without
explicit ops") we've required that file operation structures explicitly
enable splice support, rather than falling back to the default handlers.

Most /proc files use the indirect 'struct proc_ops' to describe their
file operations, and were fixed up to support splice earlier in commits
40be821d627c..b24c30c67863, but the mountinfo files interact with the
VFS directly using their own 'struct file_operations' and got missed as
a result.

This adds the necessary support for splice to work for /proc/*/mountinfo
and friends.

Reported-by: Joan Bruguera Micó <joanbrugueram@gmail.com>
Reported-by: Jussi Kivilinna <jussi.kivilinna@iki.fi>
Link: https://bugzilla.kernel.org/show_bug.cgi?id=209971
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/fs/proc_namespace.c b/fs/proc_namespace.c
index e59d4bb3a89e4429a5e2cca9ed5f22e1a6c72bfb..eafb75755fa37119ab88a1d24e688680628c08e9 100644 (file)
--- a/fs/proc_namespace.c
+++ b/fs/proc_namespace.c
@@ -320,7 +320,8 @@ static int mountstats_open(struct inode *inode, struct file *file)
 
 const struct file_operations proc_mounts_operations = {
        .open           = mounts_open,
-       .read           = seq_read,
+       .read_iter      = seq_read_iter,
+       .splice_read    = generic_file_splice_read,
        .llseek         = seq_lseek,
        .release        = mounts_release,
        .poll           = mounts_poll,
@@ -328,7 +329,8 @@ const struct file_operations proc_mounts_operations = {
 
 const struct file_operations proc_mountinfo_operations = {
        .open           = mountinfo_open,
-       .read           = seq_read,
+       .read_iter      = seq_read_iter,
+       .splice_read    = generic_file_splice_read,
        .llseek         = seq_lseek,
        .release        = mounts_release,
        .poll           = mounts_poll,
@@ -336,7 +338,8 @@ const struct file_operations proc_mountinfo_operations = {
 
 const struct file_operations proc_mountstats_operations = {
        .open           = mountstats_open,
-       .read           = seq_read,
+       .read_iter      = seq_read_iter,
+       .splice_read    = generic_file_splice_read,
        .llseek         = seq_lseek,
        .release        = mounts_release,
 };