Inorder to check whether the buffer_heads are mapped we need
to hold page lock. Otherwise a reclaim can cleanup the attached
buffer_heads.
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxxxxxxxxxx>
---
fs/ext4/inode.c | 13 +++++++++++--
1 files changed, 11 insertions(+), 2 deletions(-)
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index f9c642b..2feb2d5 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -5281,12 +5281,21 @@ int ext4_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf)
else
len = PAGE_CACHE_SIZE;
+ lock_page(page);
+ /*
+ * return if we have all the buffers mapped. This avoid
+ * the need to call write_begin/write_end which does a
+ * journal_start/journal_stop which can block and take
+ * long time
+ */
if (page_has_buffers(page)) {
- /* return if we have all the buffers mapped */
if (!walk_page_buffers(NULL, page_buffers(page), 0, len, NULL,
- ext4_bh_unmapped))
+ ext4_bh_unmapped)) {
+ unlock_page(page);
goto out_unlock;
+ }
}
+ unlock_page(page);
/*
* OK, we need to fill the hole... Do write_begin write_end
* to do block allocation/reservation.We are not holding
--
1.6.4.2.253.g0b1fac
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