[PATCH stable 2/5] fs: do not compare against ->llseek

From: Saeed Mirzamohammadi
Date: Mon Oct 17 2022 - 15:20:55 EST


From: "Jason A. Donenfeld" <Jason@xxxxxxxxx>

Now vfs_llseek() can simply check for FMODE_LSEEK; if it's set,
we know that ->llseek() won't be NULL and if it's not we should
just fail with -ESPIPE.

A couple of other places where we used to check for special
values of ->llseek() (somewhat inconsistently) switched to
checking FMODE_LSEEK.

Signed-off-by: Jason A. Donenfeld <Jason@xxxxxxxxx>
Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
(cherry picked from commit 4e3299eaddffd9d7d5b8bae28ad700bb775f02d0)
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Saeed Mirzamohammadi <saeed.mirzamohammadi@xxxxxxxxxx>
---
fs/coredump.c | 4 ++--
fs/overlayfs/copy_up.c | 3 +--
fs/read_write.c | 11 +++--------
3 files changed, 6 insertions(+), 12 deletions(-)

diff --git a/fs/coredump.c b/fs/coredump.c
index 26eb5a095832..04ce02e30e23 100644
--- a/fs/coredump.c
+++ b/fs/coredump.c
@@ -886,9 +886,9 @@ static int __dump_skip(struct coredump_params *cprm, size_t nr)
{
static char zeroes[PAGE_SIZE];
struct file *file = cprm->file;
- if (file->f_op->llseek && file->f_op->llseek != no_llseek) {
+ if (file->f_mode & FMODE_LSEEK) {
if (dump_interrupted() ||
- file->f_op->llseek(file, nr, SEEK_CUR) < 0)
+ vfs_llseek(file, nr, SEEK_CUR) < 0)
return 0;
cprm->pos += nr;
return 1;
diff --git a/fs/overlayfs/copy_up.c b/fs/overlayfs/copy_up.c
index e040970408d4..7636ec4d8b1c 100644
--- a/fs/overlayfs/copy_up.c
+++ b/fs/overlayfs/copy_up.c
@@ -226,8 +226,7 @@ static int ovl_copy_up_data(struct ovl_fs *ofs, struct path *old,
/* Couldn't clone, so now we try to copy the data */

/* Check if lower fs supports seek operation */
- if (old_file->f_mode & FMODE_LSEEK &&
- old_file->f_op->llseek)
+ if (old_file->f_mode & FMODE_LSEEK)
skip_hole = true;

while (len) {
diff --git a/fs/read_write.c b/fs/read_write.c
index 8d3ec975514d..b64527211b32 100644
--- a/fs/read_write.c
+++ b/fs/read_write.c
@@ -290,14 +290,9 @@ EXPORT_SYMBOL(default_llseek);

loff_t vfs_llseek(struct file *file, loff_t offset, int whence)
{
- loff_t (*fn)(struct file *, loff_t, int);
-
- fn = no_llseek;
- if (file->f_mode & FMODE_LSEEK) {
- if (file->f_op->llseek)
- fn = file->f_op->llseek;
- }
- return fn(file, offset, whence);
+ if (!(file->f_mode & FMODE_LSEEK))
+ return -ESPIPE;
+ return file->f_op->llseek(file, offset, whence);
}
EXPORT_SYMBOL(vfs_llseek);

--
2.31.1