cleanup may_open

Add a switch for the various i_mode fmt cases, and remove the comment
about writeability of devices nodes - that part is handled in
inode_permission and comment on (briefly) there.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

1 files changed, 12 insertions, 14 deletions

diff --git a/fs/namei.c b/fs/namei.c
index bbc15c237558..2a40409e3e03 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -1486,24 +1486,22 @@ int may_open(struct path *path, int acc_mode, int flag)
         if (!inode)
                 return -ENOENT;
 
-        if (S_ISLNK(inode->i_mode))
+        switch (inode->i_mode & S_IFMT) {
+        case S_IFLNK:
                 return -ELOOP;
-        
-        if (S_ISDIR(inode->i_mode) && (acc_mode & MAY_WRITE))
-                return -EISDIR;
-
-        /*
-         * FIFO's, sockets and device files are special: they don't
-         * actually live on the filesystem itself, and as such you
-         * can write to them even if the filesystem is read-only.
-         */
-        if (S_ISFIFO(inode->i_mode) || S_ISSOCK(inode->i_mode)) {
-                flag &= ~O_TRUNC;
-        } else if (S_ISBLK(inode->i_mode) || S_ISCHR(inode->i_mode)) {
+        case S_IFDIR:
+                if (acc_mode & MAY_WRITE)
+                        return -EISDIR;
+                break;
+        case S_IFBLK:
+        case S_IFCHR:
                 if (path->mnt->mnt_flags & MNT_NODEV)
                         return -EACCES;
-
+                /*FALLTHRU*/
+        case S_IFIFO:
+        case S_IFSOCK:
                 flag &= ~O_TRUNC;
+                break;
         }
 
         error = inode_permission(inode, acc_mode);