[PATCH v2] fs: return EPERM on immutable inode

[Eryu Guan <guaneryu@xxxxxxxxx>]

In most cases, EPERM is returned on immutable inode, and there're only a
few places returning EACCES. I noticed this when running LTP on
overlayfs, setxattr03 failed due to unexpected EACCES on immutable
inode.

So converting all EACCES to EPERM on immutable inode.

Acked-by: Dave Chinner <dchinner@xxxxxxxxxx>
Signed-off-by: Eryu Guan <guaneryu@xxxxxxxxx>
---
v2:
- update commit message to include the background on noticing this issue

 fs/gfs2/inode.c    | 2 +-
 fs/namei.c         | 2 +-
 fs/utimes.c        | 3 ++-
 fs/xfs/xfs_ioctl.c | 2 +-
 4 files changed, 5 insertions(+), 4 deletions(-)

diff --git a/fs/gfs2/inode.c b/fs/gfs2/inode.c
index bb30f9a..4c68d91 100644
--- a/fs/gfs2/inode.c
+++ b/fs/gfs2/inode.c
@@ -1757,7 +1757,7 @@ int gfs2_permission(struct inode *inode, int mask)
        }
 
        if ((mask & MAY_WRITE) && IS_IMMUTABLE(inode))
-               error = -EACCES;
+               error = -EPERM;
        else
                error = generic_permission(inode, mask);
        if (unlock)
diff --git a/fs/namei.c b/fs/namei.c
index 1d9ca2d..7f4a40a 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -408,7 +408,7 @@ int __inode_permission(struct inode *inode, int mask)
                 * Nobody gets write access to an immutable file.
                 */
                if (IS_IMMUTABLE(inode))
-                       return -EACCES;
+                       return -EPERM;
        }
 
        retval = do_inode_permission(inode, mask);
diff --git a/fs/utimes.c b/fs/utimes.c
index 85c40f4..794f5f5 100644
--- a/fs/utimes.c
+++ b/fs/utimes.c
@@ -92,10 +92,11 @@ static int utimes_common(struct path *path, struct timespec 
*times)
                 * then we need to check permissions, because
                 * inode_change_ok() won't do it.
                 */
-               error = -EACCES;
+               error = -EPERM;
                 if (IS_IMMUTABLE(inode))
                        goto mnt_drop_write_and_out;
 
+               error = -EACCES;
                if (!inode_owner_or_capable(inode)) {
                        error = inode_permission(inode, MAY_WRITE);
                        if (error)
diff --git a/fs/xfs/xfs_ioctl.c b/fs/xfs/xfs_ioctl.c
index bcb6c19..4c4c58f 100644
--- a/fs/xfs/xfs_ioctl.c
+++ b/fs/xfs/xfs_ioctl.c
@@ -232,7 +232,7 @@ xfs_open_by_handle(
        }
 
        if ((fmode & FMODE_WRITE) && IS_IMMUTABLE(inode)) {
-               error = -EACCES;
+               error = -EPERM;
                goto out_dput;
        }
 
-- 
2.5.5