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| author | Steven Rostedt (VMware) <rostedt@goodmis.org> | 2017-02-25 01:59:10 +0300 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2017-02-25 04:46:56 +0300 |
| commit | 3f472cc978ea019c7b09cc03f90b8ed6034efdf8 (patch) | |
| tree | 7744f418e1d89fc85deb14e6613b9a201dcaeba8 | |
| parent | c2f83143f1c67d186520b72b6cefbf0aa07a34ee (diff) | |
| download | linux-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.c | 2 |
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) |