mm/shmem.c: fix unlikely() test of info->seals to test only for WRITE…

… and GROW

Running my likely/unlikely profiler, I discovered that the test in
shmem_write_begin() that tests for info->seals as unlikely, is always
incorrect.  This is because shmem_get_inode() sets info->seals to have
F_SEAL_SEAL set by default, and it is unlikely to be cleared when
shmem_write_begin() is called.  Thus, the if statement is very likely.

But as the if statement block only cares about F_SEAL_WRITE and
F_SEAL_GROW, change the test to only test those two bits.

Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Steven Rostedt (VMware) <[email protected]>
Acked-by: Hugh Dickins <[email protected]>
Cc: David Herrmann <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

mm/shmem.c

@@ -2331,7 +2331,7 @@ shmem_write_begin(struct file *file, struct address_space *mapping,
 	pgoff_t index = pos >> PAGE_SHIFT;
 
 	/* i_mutex is held by caller */
-	if (unlikely(info->seals)) {
+	if (unlikely(info->seals & (F_SEAL_WRITE | F_SEAL_GROW))) {
 		if (info->seals & F_SEAL_WRITE)
 			return -EPERM;
 		if ((info->seals & F_SEAL_GROW) && pos + len > inode->i_size)