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authorTrond Myklebust <Trond.Myklebust@netapp.com>2007-05-20 10:18:27 -0400
committerTrond Myklebust <Trond.Myklebust@netapp.com>2007-05-24 10:44:20 -0400
commit7fe7f8487ae742239dd8c66596e2311c30d057d1 (patch)
treec506bd7dcacc9d5b25b3295bd1f327e534532c54 /fs/nfs/write.c
parent585a2858b970cb6e2e5ca4877eefd18b4dba8ed4 (diff)
NFS: Avoid a deadlock situation on write
When processes are allowed to attempt to lock a non-contiguous range of nfs write requests, it is possible for generic_writepages to 'wrap round' the address space, and call writepage() on a request that is already locked by the same process. We avoid the deadlock by checking if the page index is contiguous with the list of nfs write requests that is already held in our nfs_pageio_descriptor prior to attempting to lock a new request. Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Diffstat (limited to 'fs/nfs/write.c')
-rw-r--r--fs/nfs/write.c6
1 files changed, 4 insertions, 2 deletions
diff --git a/fs/nfs/write.c b/fs/nfs/write.c
index b084c03ce493..af344a158e01 100644
--- a/fs/nfs/write.c
+++ b/fs/nfs/write.c
@@ -273,8 +273,6 @@ static int nfs_page_async_flush(struct nfs_pageio_descriptor *pgio,
* request as dirty (in which case we don't care).
*/
spin_unlock(req_lock);
- /* Prevent deadlock! */
- nfs_pageio_complete(pgio);
ret = nfs_wait_on_request(req);
nfs_release_request(req);
if (ret != 0)
@@ -321,6 +319,8 @@ static int nfs_writepage_locked(struct page *page, struct writeback_control *wbc
pgio = &mypgio;
}
+ nfs_pageio_cond_complete(pgio, page->index);
+
err = nfs_page_async_flush(pgio, page);
if (err <= 0)
goto out;
@@ -329,6 +329,8 @@ static int nfs_writepage_locked(struct page *page, struct writeback_control *wbc
if (!offset)
goto out;
+ nfs_pageio_cond_complete(pgio, page->index);
+
ctx = nfs_find_open_context(inode, NULL, FMODE_WRITE);
if (ctx == NULL) {
err = -EBADF;