netfs: Change ->init_request() to return an error code

Change the request initialisation function to return an error code so that
the network filesystem can return a failure (ENOMEM, for example).

This will also allow ceph to abort a ->readahead() op if the server refuses
to give it a cap allowing local caching from within the netfslib framework
(errors aren't passed back through ->readahead(), so returning, say,
-ENOBUFS will cause the op to be aborted).

Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
cc: linux-cachefs@redhat.com

Link: https://lore.kernel.org/r/164678212401.1200972.16537041523832944934.stgit@warthog.procyon.org.uk/
Link: https://lore.kernel.org/r/164692905398.2099075.5238033621684646524.stgit@warthog.procyon.org.uk/

diff --git a/fs/9p/vfs_addr.c b/fs/9p/vfs_addr.c
index fdc1033..91d3926 100644 (file)
--- a/fs/9p/vfs_addr.c
+++ b/fs/9p/vfs_addr.c
@@ -56,12 +56,13 @@ static void v9fs_issue_read(struct netfs_io_subrequest *subreq)
  * @rreq: The read request
  * @file: The file being read from
  */
-static void v9fs_init_request(struct netfs_io_request *rreq, struct file *file)
+static int v9fs_init_request(struct netfs_io_request *rreq, struct file *file)
 {
        struct p9_fid *fid = file->private_data;
 
        refcount_inc(&fid->count);
        rreq->netfs_priv = fid;
+       return 0;
 }
 
 /**

diff --git a/fs/afs/file.c b/fs/afs/file.c
index b19d635..6469d7f 100644 (file)
--- a/fs/afs/file.c
+++ b/fs/afs/file.c
@@ -359,9 +359,10 @@ static int afs_symlink_readpage(struct file *file, struct page *page)
        return ret;
 }
 
-static void afs_init_request(struct netfs_io_request *rreq, struct file *file)
+static int afs_init_request(struct netfs_io_request *rreq, struct file *file)
 {
        rreq->netfs_priv = key_get(afs_file_key(file));
+       return 0;
 }
 
 static bool afs_is_cache_enabled(struct inode *inode)

diff --git a/fs/netfs/objects.c b/fs/netfs/objects.c
index 986d7a9..ae18827 100644 (file)
--- a/fs/netfs/objects.c
+++ b/fs/netfs/objects.c
@@ -20,27 +20,34 @@ struct netfs_io_request *netfs_alloc_request(struct address_space *mapping,
 {
        static atomic_t debug_ids;
        struct netfs_io_request *rreq;
+       int ret;
 
        rreq = kzalloc(sizeof(struct netfs_io_request), GFP_KERNEL);
-       if (rreq) {
-               rreq->start     = start;
-               rreq->len       = len;
-               rreq->origin    = origin;
-               rreq->netfs_ops = ops;
-               rreq->netfs_priv = netfs_priv;
-               rreq->mapping   = mapping;
-               rreq->inode     = file_inode(file);
-               rreq->i_size    = i_size_read(rreq->inode);
-               rreq->debug_id  = atomic_inc_return(&debug_ids);
-               INIT_LIST_HEAD(&rreq->subrequests);
-               INIT_WORK(&rreq->work, netfs_rreq_work);
-               refcount_set(&rreq->ref, 1);
-               __set_bit(NETFS_RREQ_IN_PROGRESS, &rreq->flags);
-               if (ops->init_request)
-                       ops->init_request(rreq, file);
-               netfs_stat(&netfs_n_rh_rreq);
+       if (!rreq)
+               return ERR_PTR(-ENOMEM);
+
+       rreq->start     = start;
+       rreq->len       = len;
+       rreq->origin    = origin;
+       rreq->netfs_ops = ops;
+       rreq->netfs_priv = netfs_priv;
+       rreq->mapping   = mapping;
+       rreq->inode     = file_inode(file);
+       rreq->i_size    = i_size_read(rreq->inode);
+       rreq->debug_id  = atomic_inc_return(&debug_ids);
+       INIT_LIST_HEAD(&rreq->subrequests);
+       INIT_WORK(&rreq->work, netfs_rreq_work);
+       refcount_set(&rreq->ref, 1);
+       __set_bit(NETFS_RREQ_IN_PROGRESS, &rreq->flags);
+       if (rreq->netfs_ops->init_request) {
+               ret = rreq->netfs_ops->init_request(rreq, file);
+               if (ret < 0) {
+                       kfree(rreq);
+                       return ERR_PTR(ret);
+               }
        }
 
+       netfs_stat(&netfs_n_rh_rreq);
        return rreq;
 }
 

diff --git a/fs/netfs/read_helper.c b/fs/netfs/read_helper.c
index dea0857..b5176f4 100644 (file)
--- a/fs/netfs/read_helper.c
+++ b/fs/netfs/read_helper.c
@@ -768,7 +768,7 @@ void netfs_readahead(struct readahead_control *ractl,
                                   readahead_pos(ractl),
                                   readahead_length(ractl),
                                   NETFS_READAHEAD);
-       if (!rreq)
+       if (IS_ERR(rreq))
                goto cleanup;
 
        if (ops->begin_cache_operation) {
@@ -842,11 +842,9 @@ int netfs_readpage(struct file *file,
        rreq = netfs_alloc_request(folio->mapping, file, ops, netfs_priv,
                                   folio_file_pos(folio), folio_size(folio),
                                   NETFS_READPAGE);
-       if (!rreq) {
-               if (netfs_priv)
-                       ops->cleanup(folio_file_mapping(folio), netfs_priv);
-               folio_unlock(folio);
-               return -ENOMEM;
+       if (IS_ERR(rreq)) {
+               ret = PTR_ERR(rreq);
+               goto alloc_error;
        }
 
        if (ops->begin_cache_operation) {
@@ -887,6 +885,11 @@ int netfs_readpage(struct file *file,
 out:
        netfs_put_request(rreq, false, netfs_rreq_trace_put_hold);
        return ret;
+alloc_error:
+       if (netfs_priv)
+               ops->cleanup(folio_file_mapping(folio), netfs_priv);
+       folio_unlock(folio);
+       return ret;
 }
 EXPORT_SYMBOL(netfs_readpage);
 
@@ -1007,12 +1010,13 @@ retry:
                goto have_folio_no_wait;
        }
 
-       ret = -ENOMEM;
        rreq = netfs_alloc_request(mapping, file, ops, netfs_priv,
                                   folio_file_pos(folio), folio_size(folio),
                                   NETFS_READ_FOR_WRITE);
-       if (!rreq)
+       if (IS_ERR(rreq)) {
+               ret = PTR_ERR(rreq);
                goto error;
+       }
        rreq->no_unlock_folio   = folio_index(folio);
        __set_bit(NETFS_RREQ_NO_UNLOCK_FOLIO, &rreq->flags);
        netfs_priv = NULL;

diff --git a/include/linux/netfs.h b/include/linux/netfs.h
index 7dc741d..4b99e38 100644 (file)
--- a/include/linux/netfs.h
+++ b/include/linux/netfs.h
@@ -193,7 +193,7 @@ struct netfs_io_request {
  */
 struct netfs_request_ops {
        bool (*is_cache_enabled)(struct inode *inode);
-       void (*init_request)(struct netfs_io_request *rreq, struct file *file);
+       int (*init_request)(struct netfs_io_request *rreq, struct file *file);
        int (*begin_cache_operation)(struct netfs_io_request *rreq);
        void (*expand_readahead)(struct netfs_io_request *rreq);
        bool (*clamp_length)(struct netfs_io_subrequest *subreq);