[PATCH 5.16 143/285] NFS: nfsiod should not block forever in mempool_alloc()

Greg Kroah-Hartman
2022-04-12T07:56:32Z

From: Trond Myklebust <trond.myklebust@hammerspace.com>

[ Upstream commit 515dcdcd48736576c6f5c197814da6f81c60a21e ]

The concern is that since nfsiod is sometimes required to kick off a
commit, it can get locked up waiting forever in mempool_alloc() instead
of failing gracefully and leaving the commit until later.

Try to allocate from the slab first, with GFP_KERNEL | __GFP_NORETRY,
then fall back to a non-blocking attempt to allocate from the memory
pool.

Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
fs/nfs/internal.h | 7 +++++++
fs/nfs/pnfs_nfs.c | 8 ++++++--
fs/nfs/write.c | 24 +++++++++---------------
include/linux/nfs_fs.h | 2 +-
4 files changed, 23 insertions(+), 18 deletions(-)

diff --git a/fs/nfs/internal.h b/fs/nfs/internal.h
index 12f6acb483bb..85957db80975 100644
--- a/fs/nfs/internal.h
+++ b/fs/nfs/internal.h
@@ -572,6 +572,13 @@ nfs_write_match_verf(const struct nfs_writeverf *verf,
!nfs_write_verifier_cmp(&req->wb_verf, &verf->verifier);
}

+static inline gfp_t nfs_io_gfp_mask(void)
+{
+ if (current->flags & PF_WQ_WORKER)
+ return GFP_KERNEL | __GFP_NORETRY | __GFP_NOWARN;
+ return GFP_KERNEL;
+}
+
/* unlink.c */
extern struct rpc_task *
nfs_async_rename(struct inode *old_dir, struct inode *new_dir,
diff --git a/fs/nfs/pnfs_nfs.c b/fs/nfs/pnfs_nfs.c
index 316f68f96e57..657c242a18ff 100644
--- a/fs/nfs/pnfs_nfs.c
+++ b/fs/nfs/pnfs_nfs.c
@@ -419,7 +419,7 @@ static struct nfs_commit_data *
pnfs_bucket_fetch_commitdata(struct pnfs_commit_bucket *bucket,
struct nfs_commit_info *cinfo)
{
- struct nfs_commit_data *data = nfs_commitdata_alloc(false);
+ struct nfs_commit_data *data = nfs_commitdata_alloc();

if (!data)
return NULL;
@@ -515,7 +515,11 @@ pnfs_generic_commit_pagelist(struct inode *inode, struct list_head *mds_pages,
unsigned int nreq = 0;

if (!list_empty(mds_pages)) {
- data = nfs_commitdata_alloc(true);
+ data = nfs_commitdata_alloc();
+ if (!data) {
+ nfs_retry_commit(mds_pages, NULL, cinfo, -1);
+ return -ENOMEM;
+ }
data->ds_commit_index = -1;
list_splice_init(mds_pages, &data->pages);
list_add_tail(&data->list, &list);
diff --git a/fs/nfs/write.c b/fs/nfs/write.c
index e86aff429993..8eb7466182ac 100644
--- a/fs/nfs/write.c
+++ b/fs/nfs/write.c
@@ -70,27 +70,17 @@ static mempool_t *nfs_wdata_mempool;
static struct kmem_cache *nfs_cdata_cachep;
static mempool_t *nfs_commit_mempool;

-struct nfs_commit_data *nfs_commitdata_alloc(bool never_fail)
+struct nfs_commit_data *nfs_commitdata_alloc(void)
{
struct nfs_commit_data *p;

- if (never_fail)
- p = mempool_alloc(nfs_commit_mempool, GFP_NOIO);
- else {
- /* It is OK to do some reclaim, not no safe to wait
- * for anything to be returned to the pool.
- * mempool_alloc() cannot handle that particular combination,
- * so we need two separate attempts.
- */
+ p = kmem_cache_zalloc(nfs_cdata_cachep, nfs_io_gfp_mask());
+ if (!p) {
p = mempool_alloc(nfs_commit_mempool, GFP_NOWAIT);
- if (!p)
- p = kmem_cache_alloc(nfs_cdata_cachep, GFP_NOIO |
- __GFP_NOWARN | __GFP_NORETRY);
if (!p)
return NULL;
+ memset(p, 0, sizeof(*p));
}
-
- memset(p, 0, sizeof(*p));
INIT_LIST_HEAD(&p->pages);
return p;
}
@@ -1825,7 +1815,11 @@ nfs_commit_list(struct inode *inode, struct list_head *head, int how,
if (list_empty(head))
return 0;

- data = nfs_commitdata_alloc(true);
+ data = nfs_commitdata_alloc();
+ if (!data) {
+ nfs_retry_commit(head, NULL, cinfo, -1);
+ return -ENOMEM;
+ }

/* Set up the argument struct */
nfs_init_commit(data, head, NULL, cinfo);
diff --git a/include/linux/nfs_fs.h b/include/linux/nfs_fs.h
index 92525222abfd..445e9343be3e 100644
--- a/include/linux/nfs_fs.h
+++ b/include/linux/nfs_fs.h
@@ -584,7 +584,7 @@ extern int nfs_wb_all(struct inode *inode);
extern int nfs_wb_page(struct inode *inode, struct page *page);
extern int nfs_wb_page_cancel(struct inode *inode, struct page* page);
extern int nfs_commit_inode(struct inode *, int);
-extern struct nfs_commit_data *nfs_commitdata_alloc(bool never_fail);
+extern struct nfs_commit_data *nfs_commitdata_alloc(void);
extern void nfs_commit_free(struct nfs_commit_data *data);
bool nfs_commit_end(struct nfs_mds_commit_info *cinfo);

--
2.35.1