Messages in this thread Patch in this message | | | Date | Fri, 3 Feb 2017 10:56:56 -0500 | From | "Steven Rostedt (VMware)" <> | Subject | [PATCH] shm: Fix unlikely() test of info->seals to test only for WRITE and GROW |
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From: "Steven Rostedt (VMware)" <rostedt@goodmis.org>
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.
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> --- mm/shmem.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/mm/shmem.c b/mm/shmem.c index bb53285..ef4cdbb 100644 --- a/mm/shmem.c +++ b/mm/shmem.c @@ -2194,7 +2194,7 @@ 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) -- 2.9.3
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