NFS: nfsiod should not block forever in mempool_alloc()

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>

diff --git a/fs/nfs/internal.h b/fs/nfs/internal.h
index 194840a..57b0497 100644 (file)
--- a/fs/nfs/internal.h
+++ b/fs/nfs/internal.h
@@ -587,6 +587,13 @@ 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 316f68f..657c242 100644 (file)
--- 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 599a824..ef47e37 100644 (file)
--- 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;
 }
@@ -1826,7 +1816,11 @@ 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 c47c448..db305ab 100644 (file)
--- a/include/linux/nfs_fs.h
+++ b/include/linux/nfs_fs.h
@@ -580,7 +580,7 @@ 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);