Implement stacked fadvise to fix syscalls readahead(2) and fadvise64(2)
on an overlayfs file.
Suggested-by: Miklos Szeredi <mszeredi@xxxxxxxxxx>
Fixes: d1d04ef8572b ("ovl: stack file ops")
Signed-off-by: Amir Goldstein <amir73il@xxxxxxxxx>
---
Miklos,
Following v4 with ovl_override_creds.
Thanks,
Amir.
fs/overlayfs/file.c | 20 ++++++++++++++++++++
1 file changed, 20 insertions(+)
diff --git a/fs/overlayfs/file.c b/fs/overlayfs/file.c
index a4acd84591d4..89f9e97c0452 100644
--- a/fs/overlayfs/file.c
+++ b/fs/overlayfs/file.c
@@ -331,6 +331,25 @@ static long ovl_fallocate(struct file *file, int mode, loff_t offset, loff_t len
return ret;
}
+int ovl_fadvise(struct file *file, loff_t offset, loff_t len, int advice)
+{
+ struct fd real;
+ const struct cred *old_cred;
+ int ret;
+
+ ret = ovl_real_fdget(file, &real);
+ if (ret)
+ return ret;
+
+ old_cred = ovl_override_creds(file_inode(file)->i_sb);
+ ret = vfs_fadvise(real.file, offset, len, advice);
+ revert_creds(old_cred);
+
+ fdput(real);
+
+ return ret;
+}
+
static long ovl_real_ioctl(struct file *file, unsigned int cmd,
unsigned long arg)
{
@@ -499,6 +518,7 @@ const struct file_operations ovl_file_operations = {
.fsync = ovl_fsync,
.mmap = ovl_mmap,
.fallocate = ovl_fallocate,
+ .fadvise = ovl_fadvise,
.unlocked_ioctl = ovl_ioctl,
.compat_ioctl = ovl_compat_ioctl,
--
2.7.4
