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authorSteven Rostedt (VMware) <rostedt@goodmis.org>2017-02-25 01:59:10 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2017-02-25 04:46:56 +0300
commit3f472cc978ea019c7b09cc03f90b8ed6034efdf8 (patch)
tree7744f418e1d89fc85deb14e6613b9a201dcaeba8
parentc2f83143f1c67d186520b72b6cefbf0aa07a34ee (diff)
downloadlinux-3f472cc978ea019c7b09cc03f90b8ed6034efdf8.tar.xz
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/20170203105656.7aec6237@gandalf.local.home Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Acked-by: Hugh Dickins <hughd@google.com> Cc: David Herrmann <dh.herrmann@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--mm/shmem.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/mm/shmem.c b/mm/shmem.c
index f7f2330c6cb6..a26649a6633f 100644
--- a/mm/shmem.c
+++ b/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)