9p: Change p9_fid_create calling convention

Return NULL instead of ERR_PTR when we can't allocate a FID.  The ENOSPC
return value was getting all the way back to userspace, and that's
confusing for a userspace program which isn't expecting read() to tell it
there's no space left on the filesystem.  The best error we can return to
indicate a temporary failure caused by lack of client resources is ENOMEM.

Maybe it would be better to sleep until a FID is available, but that's
not a change I'm comfortable making.

Link: http://lkml.kernel.org/r/20180711210225.19730-3-willy@infradead.org
Signed-off-by: Matthew Wilcox <willy@infradead.org>
Reviewed-by: Jun Piao <piaojun@huawei.com>
Reviewed-by: Greg Kurz <groug@kaod.org>
Reviewed-by: Yiwen Jiang <jiangyiwen@huwei.com>
Cc: Eric Van Hensbergen <ericvh@gmail.com>
Cc: Ron Minnich <rminnich@sandia.gov>
Cc: Latchesar Ionkov <lucho@ionkov.net>
Signed-off-by: Dominique Martinet <dominique.martinet@cea.fr>

1 files changed, 9 insertions, 14 deletions

diff --git a/net/9p/client.c b/net/9p/client.c
index cae1fb43bd16..7c317d39bf62 100644
--- a/net/9p/client.c
+++ b/net/9p/client.c
@@ -914,13 +914,11 @@ static struct p9_fid *p9_fid_create(struct p9_client *clnt)
         p9_debug(P9_DEBUG_FID, "clnt %p\n", clnt);
         fid = kmalloc(sizeof(struct p9_fid), GFP_KERNEL);
         if (!fid)
-                return ERR_PTR(-ENOMEM);
+                return NULL;
 
         ret = p9_idpool_get(clnt->fidpool);
-        if (ret < 0) {
-                ret = -ENOSPC;
+        if (ret < 0)
                 goto error;
-        }
         fid->fid = ret;
 
         memset(&fid->qid, 0, sizeof(struct p9_qid));
@@ -936,7 +934,7 @@ static struct p9_fid *p9_fid_create(struct p9_client *clnt)
 
 error:
         kfree(fid);
-        return ERR_PTR(ret);
+        return NULL;
 }
 
 static void p9_fid_destroy(struct p9_fid *fid)
@@ -1138,9 +1136,8 @@ struct p9_fid *p9_client_attach(struct p9_client *clnt, struct p9_fid *afid,
         p9_debug(P9_DEBUG_9P, ">>> TATTACH afid %d uname %s aname %s\n",
                  afid ? afid->fid : -1, uname, aname);
         fid = p9_fid_create(clnt);
-        if (IS_ERR(fid)) {
-                err = PTR_ERR(fid);
-                fid = NULL;
+        if (!fid) {
+                err = -ENOMEM;
                 goto error;
         }
         fid->uid = n_uname;
@@ -1189,9 +1186,8 @@ struct p9_fid *p9_client_walk(struct p9_fid *oldfid, uint16_t nwname,
         clnt = oldfid->clnt;
         if (clone) {
                 fid = p9_fid_create(clnt);
-                if (IS_ERR(fid)) {
-                        err = PTR_ERR(fid);
-                        fid = NULL;
+                if (!fid) {
+                        err = -ENOMEM;
                         goto error;
                 }
 
@@ -2019,9 +2015,8 @@ struct p9_fid *p9_client_xattrwalk(struct p9_fid *file_fid,
         err = 0;
         clnt = file_fid->clnt;
         attr_fid = p9_fid_create(clnt);
-        if (IS_ERR(attr_fid)) {
-                err = PTR_ERR(attr_fid);
-                attr_fid = NULL;
+        if (!attr_fid) {
+                err = -ENOMEM;
                 goto error;
         }
         p9_debug(P9_DEBUG_9P,