Since the commit list is not ordered, it is possible for nfs_scan_commit_list
to hold a request that nfs_lock_and_join_requests() is waiting for, while
at the same time trying to grab a request that nfs_lock_and_join_requests
already holds.
Signed-off-by: Trond Myklebust <[email protected]>
---
fs/nfs/pnfs_nfs.c | 16 +++++++++++-----
fs/nfs/write.c | 15 +++++++++++----
2 files changed, 22 insertions(+), 9 deletions(-)
diff --git a/fs/nfs/pnfs_nfs.c b/fs/nfs/pnfs_nfs.c
index 303ff171cb5d..d03d836b6ee0 100644
--- a/fs/nfs/pnfs_nfs.c
+++ b/fs/nfs/pnfs_nfs.c
@@ -91,22 +91,28 @@ 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;
+ struct nfs_page *req, *tmp;
int ret = 0;
- while(!list_empty(src)) {
- req = list_first_entry(src, struct nfs_page, wb_list);
-
+restart:
+ list_for_each_entry_safe(req, tmp, src, wb_list) {
kref_get(&req->wb_kref);
if (!nfs_lock_request(req)) {
int status;
+
+ /* Prevent deadlock with nfs_lock_and_join_requests */
+ if (!list_empty(dst)) {
+ nfs_release_request(req);
+ continue;
+ }
+ /* Ensure we make progress to prevent livelock */
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;
+ goto restart;
}
nfs_request_remove_commit_list(req, cinfo);
clear_bit(PG_COMMIT_TO_DS, &req->wb_flags);
diff --git a/fs/nfs/write.c b/fs/nfs/write.c
index ae26775b5448..c3f627b08ec6 100644
--- a/fs/nfs/write.c
+++ b/fs/nfs/write.c
@@ -1028,21 +1028,28 @@ int
nfs_scan_commit_list(struct list_head *src, struct list_head *dst,
struct nfs_commit_info *cinfo, int max)
{
- struct nfs_page *req;
+ struct nfs_page *req, *tmp;
int ret = 0;
- while(!list_empty(src)) {
- req = list_first_entry(src, struct nfs_page, wb_list);
+restart:
+ list_for_each_entry_safe(req, tmp, src, wb_list) {
kref_get(&req->wb_kref);
if (!nfs_lock_request(req)) {
int status;
+
+ /* Prevent deadlock with nfs_lock_and_join_requests */
+ if (!list_empty(dst)) {
+ nfs_release_request(req);
+ continue;
+ }
+ /* Ensure we make progress to prevent livelock */
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;
+ goto restart;
}
nfs_request_remove_commit_list(req, cinfo);
nfs_list_add_request(req, dst);
--
2.13.5
It's pretty much a duplicate of nfs_scan_commit_list() that also
clears the PG_COMMIT_TO_DS flag.
Signed-off-by: Trond Myklebust <[email protected]>
---
fs/nfs/pnfs_nfs.c | 43 ++-----------------------------------------
fs/nfs/write.c | 2 ++
2 files changed, 4 insertions(+), 41 deletions(-)
diff --git a/fs/nfs/pnfs_nfs.c b/fs/nfs/pnfs_nfs.c
index d03d836b6ee0..60da59be83b6 100644
--- a/fs/nfs/pnfs_nfs.c
+++ b/fs/nfs/pnfs_nfs.c
@@ -88,44 +88,6 @@ pnfs_generic_clear_request_commit(struct nfs_page *req,
EXPORT_SYMBOL_GPL(pnfs_generic_clear_request_commit);
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;
- int ret = 0;
-
-restart:
- list_for_each_entry_safe(req, tmp, src, wb_list) {
- kref_get(&req->wb_kref);
- if (!nfs_lock_request(req)) {
- int status;
-
- /* Prevent deadlock with nfs_lock_and_join_requests */
- if (!list_empty(dst)) {
- nfs_release_request(req);
- continue;
- }
- /* Ensure we make progress to prevent livelock */
- 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;
- goto restart;
- }
- nfs_request_remove_commit_list(req, cinfo);
- clear_bit(PG_COMMIT_TO_DS, &req->wb_flags);
- nfs_list_add_request(req, dst);
- ret++;
- if ((ret == max) && !cinfo->dreq)
- break;
- cond_resched();
- }
- return ret;
-}
-
-static int
pnfs_generic_scan_ds_commit_list(struct pnfs_commit_bucket *bucket,
struct nfs_commit_info *cinfo,
int max)
@@ -135,7 +97,7 @@ pnfs_generic_scan_ds_commit_list(struct pnfs_commit_bucket *bucket,
int ret;
lockdep_assert_held(&NFS_I(cinfo->inode)->commit_mutex);
- ret = pnfs_generic_transfer_commit_list(src, dst, cinfo, max);
+ ret = nfs_scan_commit_list(src, dst, cinfo, max);
if (ret) {
cinfo->ds->nwritten -= ret;
cinfo->ds->ncommitting += ret;
@@ -180,8 +142,7 @@ void pnfs_generic_recover_commit_reqs(struct list_head *dst,
lockdep_assert_held(&NFS_I(cinfo->inode)->commit_mutex);
restart:
for (i = 0, b = cinfo->ds->buckets; i < cinfo->ds->nbuckets; i++, b++) {
- nwritten = pnfs_generic_transfer_commit_list(&b->written,
- dst, cinfo, 0);
+ nwritten = nfs_scan_commit_list(&b->written, dst, cinfo, 0);
if (!nwritten)
continue;
cinfo->ds->nwritten -= nwritten;
diff --git a/fs/nfs/write.c b/fs/nfs/write.c
index c3f627b08ec6..121218d4e5ed 100644
--- a/fs/nfs/write.c
+++ b/fs/nfs/write.c
@@ -1052,6 +1052,7 @@ nfs_scan_commit_list(struct list_head *src, struct list_head *dst,
goto restart;
}
nfs_request_remove_commit_list(req, cinfo);
+ clear_bit(PG_COMMIT_TO_DS, &req->wb_flags);
nfs_list_add_request(req, dst);
ret++;
if ((ret == max) && !cinfo->dreq)
@@ -1060,6 +1061,7 @@ nfs_scan_commit_list(struct list_head *src, struct list_head *dst,
}
return ret;
}
+EXPORT_SYMBOL_GPL(nfs_scan_commit_list);
/*
* nfs_scan_commit - Scan an inode for commit requests
--
2.13.5