[PATCH 3.16 164/357] nfs: check wait_on_bit_lock err in page_group_lock

From: Greg Kroah-Hartman
Date: Fri Oct 03 2014 - 20:27:02 EST


3.16-stable review patch. If anyone has any objections, please let me know.

------------------


From: Weston Andros Adamson <dros@xxxxxxxxxxxxxxx>

commit e7029206ff43f6cf7d6fcb741adb126f47200516 upstream.

Return errors from wait_on_bit_lock from nfs_page_group_lock.

Add a bool argument @wait to nfs_page_group_lock. If true, loop over
wait_on_bit_lock until it returns cleanly. If false, return the error
from wait_on_bit_lock.

Signed-off-by: Weston Andros Adamson <dros@xxxxxxxxxxxxxxx>
Signed-off-by: Trond Myklebust <trond.myklebust@xxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
fs/nfs/pagelist.c | 29 +++++++++++++++++++++++------
fs/nfs/write.c | 6 ++++--
include/linux/nfs_page.h | 2 +-
3 files changed, 28 insertions(+), 9 deletions(-)

--- a/fs/nfs/pagelist.c
+++ b/fs/nfs/pagelist.c
@@ -147,17 +147,25 @@ static int nfs_wait_bit_uninterruptible(
* @req - request in group that is to be locked
*
* this lock must be held if modifying the page group list
+ *
+ * returns result from wait_on_bit_lock: 0 on success, < 0 on error
*/
-void
-nfs_page_group_lock(struct nfs_page *req)
+int
+nfs_page_group_lock(struct nfs_page *req, bool wait)
{
struct nfs_page *head = req->wb_head;
+ int ret;

WARN_ON_ONCE(head != head->wb_head);

- wait_on_bit_lock(&head->wb_flags, PG_HEADLOCK,
+ do {
+ ret = wait_on_bit_lock(&head->wb_flags, PG_HEADLOCK,
nfs_wait_bit_uninterruptible,
TASK_UNINTERRUPTIBLE);
+ } while (wait && ret != 0);
+
+ WARN_ON_ONCE(ret > 0);
+ return ret;
}

/*
@@ -218,7 +226,7 @@ bool nfs_page_group_sync_on_bit(struct n
{
bool ret;

- nfs_page_group_lock(req);
+ nfs_page_group_lock(req, true);
ret = nfs_page_group_sync_on_bit_locked(req, bit);
nfs_page_group_unlock(req);

@@ -859,8 +867,13 @@ static int __nfs_pageio_add_request(stru
struct nfs_page *subreq;
unsigned int bytes_left = 0;
unsigned int offset, pgbase;
+ int ret;

- nfs_page_group_lock(req);
+ ret = nfs_page_group_lock(req, false);
+ if (ret < 0) {
+ desc->pg_error = ret;
+ return 0;
+ }

subreq = req;
bytes_left = subreq->wb_bytes;
@@ -882,7 +895,11 @@ static int __nfs_pageio_add_request(stru
if (desc->pg_recoalesce)
return 0;
/* retry add_request for this subreq */
- nfs_page_group_lock(req);
+ ret = nfs_page_group_lock(req, false);
+ if (ret < 0) {
+ desc->pg_error = ret;
+ return 0;
+ }
continue;
}

--- a/fs/nfs/write.c
+++ b/fs/nfs/write.c
@@ -216,7 +216,7 @@ static bool nfs_page_group_covers_page(s
unsigned int pos = 0;
unsigned int len = nfs_page_length(req->wb_page);

- nfs_page_group_lock(req);
+ nfs_page_group_lock(req, true);

do {
tmp = nfs_page_group_search_locked(req->wb_head, pos);
@@ -456,7 +456,9 @@ try_again:
}

/* lock each request in the page group */
- nfs_page_group_lock(head);
+ ret = nfs_page_group_lock(head, false);
+ if (ret < 0)
+ return ERR_PTR(ret);
subreq = head;
do {
/*
--- a/include/linux/nfs_page.h
+++ b/include/linux/nfs_page.h
@@ -120,7 +120,7 @@ extern size_t nfs_generic_pg_test(struct
extern int nfs_wait_on_request(struct nfs_page *);
extern void nfs_unlock_request(struct nfs_page *req);
extern void nfs_unlock_and_release_request(struct nfs_page *);
-extern void nfs_page_group_lock(struct nfs_page *);
+extern int nfs_page_group_lock(struct nfs_page *, bool);
extern void nfs_page_group_unlock(struct nfs_page *);
extern bool nfs_page_group_sync_on_bit(struct nfs_page *, unsigned int);



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