[PATCH 2/8] swap: lock i_mutex for swap_writepage direct_IO

From: Omar Sandoval
Date: Mon Dec 15 2014 - 00:29:12 EST


The generic write code locks i_mutex for a direct_IO. Swap-over-NFS
doesn't grab the mutex because nfs_direct_IO doesn't expect i_mutex to
be held, but most direct_IO implementations do.

Signed-off-by: Omar Sandoval <osandov@xxxxxxxxxxx>
---
mm/page_io.c | 3 +++
1 file changed, 3 insertions(+)

diff --git a/mm/page_io.c b/mm/page_io.c
index 955db8b..1630ac0 100644
--- a/mm/page_io.c
+++ b/mm/page_io.c
@@ -263,6 +263,7 @@ int __swap_writepage(struct page *page, struct writeback_control *wbc,
if (sis->flags & SWP_FILE) {
struct kiocb kiocb;
struct file *swap_file = sis->swap_file;
+ struct inode *inode = file_inode(swap_file);
struct address_space *mapping = swap_file->f_mapping;
struct bio_vec bv = {
.bv_page = page,
@@ -283,9 +284,11 @@ int __swap_writepage(struct page *page, struct writeback_control *wbc,

set_page_writeback(page);
unlock_page(page);
+ mutex_lock(&inode->i_mutex);
ret = mapping->a_ops->direct_IO(ITER_BVEC | WRITE,
&kiocb, &from,
kiocb.ki_pos);
+ mutex_unlock(&inode->i_mutex);
if (ret == PAGE_SIZE) {
count_vm_event(PSWPOUT);
ret = 0;
--
2.1.3

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