From 25bad1f13d138f2acce41379c2542c313c0a88b1 Mon Sep 17 00:00:00 2001
From: Davidlohr Bueso <dave@stgolabs.net>
Date: Fri, 12 Dec 2014 16:54:39 -0800
Subject: [PATCH] mm/nommu: share the i_mmap_rwsem
Shrinking/truncate logic can call nommu_shrink_inode_mappings() to verify
that any shared mappings of the inode in question aren't broken (dead
zone). afaict the only user being ramfs to handle the size change
attribute.
Pretty much a no-brainer to share the lock.
Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
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: Rik van Riel <riel@redhat.com>
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>
---
mm/nommu.c | 9 ++++-----
1 file changed, 4 insertions(+), 5 deletions(-)
diff --git a/mm/nommu.c b/mm/nommu.c
index 52a5765535811..cd519e1cd8a7a 100644
--- a/mm/nommu.c
+++ b/mm/nommu.c
@@ -2094,14 +2094,14 @@ int nommu_shrink_inode_mappings(struct inode *inode, size_t size,
high = (size + PAGE_SIZE - 1) >> PAGE_SHIFT;
down_write(&nommu_region_sem);
- i_mmap_lock_write(inode->i_mapping);
+ i_mmap_lock_read(inode->i_mapping);
/* search for VMAs that fall within the dead zone */
vma_interval_tree_foreach(vma, &inode->i_mapping->i_mmap, low, high) {
/* found one - only interested if it's shared out of the page
* cache */
if (vma->vm_flags & VM_SHARED) {
- i_mmap_unlock_write(inode->i_mapping);
+ i_mmap_unlock_read(inode->i_mapping);
up_write(&nommu_region_sem);
return -ETXTBSY; /* not quite true, but near enough */
}
@@ -2113,8 +2113,7 @@ int nommu_shrink_inode_mappings(struct inode *inode, size_t size,
* we don't check for any regions that start beyond the EOF as there
* shouldn't be any
*/
- vma_interval_tree_foreach(vma, &inode->i_mapping->i_mmap,
- 0, ULONG_MAX) {
+ vma_interval_tree_foreach(vma, &inode->i_mapping->i_mmap, 0, ULONG_MAX) {
if (!(vma->vm_flags & VM_SHARED))
continue;
@@ -2129,7 +2128,7 @@ int nommu_shrink_inode_mappings(struct inode *inode, size_t size,
}
}
- i_mmap_unlock_write(inode->i_mapping);
+ i_mmap_unlock_read(inode->i_mapping);
up_write(&nommu_region_sem);
return 0;
}
--
2.39.5