NFS: Wait for requests that are locked on the commit list

If a request is on the commit list, but is locked, we will currently skip
it, which can lead to livelocking when the commit count doesn't reduce
to zero.

Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>

diff --git a/fs/nfs/pagelist.c b/fs/nfs/pagelist.c
index ec97c301899b366c6ac1f4a7bb39a806e87fb382..548ebc7256fffac255e5af0eb4c1e2d655b442b3 100644 (file)
--- a/fs/nfs/pagelist.c
+++ b/fs/nfs/pagelist.c
@@ -434,6 +434,7 @@ void nfs_release_request(struct nfs_page *req)
 {
        kref_put(&req->wb_kref, nfs_page_group_destroy);
 }
+EXPORT_SYMBOL_GPL(nfs_release_request);
 
 /**
  * nfs_wait_on_request - Wait for a request to complete.
@@ -452,6 +453,7 @@ nfs_wait_on_request(struct nfs_page *req)
        return wait_on_bit_io(&req->wb_flags, PG_BUSY,
                              TASK_UNINTERRUPTIBLE);
 }
+EXPORT_SYMBOL_GPL(nfs_wait_on_request);
 
 /*
  * nfs_generic_pg_test - determine if requests can be coalesced

diff --git a/fs/nfs/pnfs_nfs.c b/fs/nfs/pnfs_nfs.c
index 4b0a809653d185fb451a1578c29a36aec1606957..303ff171cb5df332fed2b25bee416007c7d693c9 100644 (file)
--- a/fs/nfs/pnfs_nfs.c
+++ b/fs/nfs/pnfs_nfs.c
@@ -91,13 +91,23 @@ static int
 pnfs_generic_transfer_commit_list(struct list_head *src, struct list_head *dst,
                                  struct nfs_commit_info *cinfo, int max)
 {
-       struct nfs_page *req, *tmp;
+       struct nfs_page *req;
        int ret = 0;
 
-       list_for_each_entry_safe(req, tmp, src, wb_list) {
-               if (!nfs_lock_request(req))
-                       continue;
+       while(!list_empty(src)) {
+               req = list_first_entry(src, struct nfs_page, wb_list);
+
                kref_get(&req->wb_kref);
+               if (!nfs_lock_request(req)) {
+                       int status;
+                       mutex_unlock(&NFS_I(cinfo->inode)->commit_mutex);
+                       status = nfs_wait_on_request(req);
+                       nfs_release_request(req);
+                       mutex_lock(&NFS_I(cinfo->inode)->commit_mutex);
+                       if (status < 0)
+                               break;
+                       continue;
+               }
                nfs_request_remove_commit_list(req, cinfo);
                clear_bit(PG_COMMIT_TO_DS, &req->wb_flags);
                nfs_list_add_request(req, dst);

diff --git a/fs/nfs/write.c b/fs/nfs/write.c
index 86670282386901ee29f17424497342bb0da316b4..5dd3b212376e96d68947c5c864ae32cfacefb59e 100644 (file)
--- a/fs/nfs/write.c
+++ b/fs/nfs/write.c
@@ -1030,13 +1030,22 @@ int
 nfs_scan_commit_list(struct list_head *src, struct list_head *dst,
                     struct nfs_commit_info *cinfo, int max)
 {
-       struct nfs_page *req, *tmp;
+       struct nfs_page *req;
        int ret = 0;
 
-       list_for_each_entry_safe(req, tmp, src, wb_list) {
-               if (!nfs_lock_request(req))
-                       continue;
+       while(!list_empty(src)) {
+               req = list_first_entry(src, struct nfs_page, wb_list);
                kref_get(&req->wb_kref);
+               if (!nfs_lock_request(req)) {
+                       int status;
+                       mutex_unlock(&NFS_I(cinfo->inode)->commit_mutex);
+                       status = nfs_wait_on_request(req);
+                       nfs_release_request(req);
+                       mutex_lock(&NFS_I(cinfo->inode)->commit_mutex);
+                       if (status < 0)
+                               break;
+                       continue;
+               }
                nfs_request_remove_commit_list(req, cinfo);
                nfs_list_add_request(req, dst);
                ret++;