mm/rmap: share the i_mmap_rwsem
authorDavidlohr Bueso <dave@stgolabs.net>
Sat, 13 Dec 2014 00:54:27 +0000 (16:54 -0800)
committerLinus Torvalds <torvalds@linux-foundation.org>
Sat, 13 Dec 2014 20:42:45 +0000 (12:42 -0800)
Similarly to the anon memory counterpart, we can share the mapping's lock
ownership as the interval tree is not modified when doing doing the walk,
only the file page.

Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
Acked-by: Rik van Riel <riel@redhat.com>
Acked-by: "Kirill A. Shutemov" <kirill@shutemov.name>
Acked-by: Hugh Dickins <hughd@google.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Acked-by: Mel Gorman <mgorman@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
include/linux/fs.h
mm/rmap.c

index 6abcd0b72ae001583f9072ca2be010fafadc0cf3..1d1838de6882a6378e4210c63799443803ec4c42 100644 (file)
@@ -478,6 +478,16 @@ static inline void i_mmap_unlock_write(struct address_space *mapping)
        up_write(&mapping->i_mmap_rwsem);
 }
 
+static inline void i_mmap_lock_read(struct address_space *mapping)
+{
+       down_read(&mapping->i_mmap_rwsem);
+}
+
+static inline void i_mmap_unlock_read(struct address_space *mapping)
+{
+       up_read(&mapping->i_mmap_rwsem);
+}
+
 /*
  * Might pages of this file be mapped into userspace?
  */
index 18247f89f1a884598971b4c6d3a9591eb11ee84c..14ad2b3b0f543dfd196d611d41de16502d054663 100644 (file)
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -1690,7 +1690,8 @@ static int rmap_walk_file(struct page *page, struct rmap_walk_control *rwc)
 
        if (!mapping)
                return ret;
-       i_mmap_lock_write(mapping);
+
+       i_mmap_lock_read(mapping);
        vma_interval_tree_foreach(vma, &mapping->i_mmap, pgoff, pgoff) {
                unsigned long address = vma_address(page, vma);
 
@@ -1711,9 +1712,8 @@ static int rmap_walk_file(struct page *page, struct rmap_walk_control *rwc)
                goto done;
 
        ret = rwc->file_nonlinear(page, mapping, rwc->arg);
-
 done:
-       i_mmap_unlock_write(mapping);
+       i_mmap_unlock_read(mapping);
        return ret;
 }