This is a note to let you know that I've just added the patch titled
nfsd: Extend the mutex holding region around in nfsd4_process_open2()
to the 4.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
nfsd-extend-the-mutex-holding-region-around-in-nfsd4_process_open2.patch
and it can be found in the queue-4.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 5cc1fb2a093e254b656c64ff24b0b76bed1d34d9 Mon Sep 17 00:00:00 2001
From: Oleg Drokin <green@xxxxxxxxxxxxxx>
Date: Tue, 14 Jun 2016 23:28:05 -0400
Subject: nfsd: Extend the mutex holding region around in nfsd4_process_open2()
From: Oleg Drokin <green@xxxxxxxxxxxxxx>
commit 5cc1fb2a093e254b656c64ff24b0b76bed1d34d9 upstream.
To avoid racing entry into nfs4_get_vfs_file().
Make init_open_stateid() return with locked stateid to be unlocked
by the caller.
Signed-off-by: Oleg Drokin <green@xxxxxxxxxxxxxx>
Signed-off-by: J. Bruce Fields <bfields@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
fs/nfsd/nfs4state.c | 16 +++++++++++++---
1 file changed, 13 insertions(+), 3 deletions(-)
--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c
@@ -3452,6 +3452,10 @@ init_open_stateid(struct nfs4_ol_stateid
struct nfs4_openowner *oo = open->op_openowner;
struct nfs4_ol_stateid *retstp = NULL;
+ /* We are moving these outside of the spinlocks to avoid the warnings */
+ mutex_init(&stp->st_mutex);
+ mutex_lock(&stp->st_mutex);
+
spin_lock(&oo->oo_owner.so_client->cl_lock);
spin_lock(&fp->fi_lock);
@@ -3467,13 +3471,17 @@ init_open_stateid(struct nfs4_ol_stateid
stp->st_access_bmap = 0;
stp->st_deny_bmap = 0;
stp->st_openstp = NULL;
- mutex_init(&stp->st_mutex);
list_add(&stp->st_perstateowner, &oo->oo_owner.so_stateids);
list_add(&stp->st_perfile, &fp->fi_stateids);
out_unlock:
spin_unlock(&fp->fi_lock);
spin_unlock(&oo->oo_owner.so_client->cl_lock);
+ if (retstp) {
+ mutex_lock(&retstp->st_mutex);
+ /* Not that we need to, just for neatness */
+ mutex_unlock(&stp->st_mutex);
+ }
return retstp;
}
@@ -4309,11 +4317,14 @@ nfsd4_process_open2(struct svc_rqst *rqs
} else {
stp = open->op_stp;
open->op_stp = NULL;
+ /*
+ * init_open_stateid() either returns a locked stateid
+ * it found, or initializes and locks the new one we passed in
+ */
swapstp = init_open_stateid(stp, fp, open);
if (swapstp) {
nfs4_put_stid(&stp->st_stid);
stp = swapstp;
- mutex_lock(&stp->st_mutex);
status = nfs4_upgrade_open(rqstp, fp, current_fh,
stp, open);
if (status) {
@@ -4322,7 +4333,6 @@ nfsd4_process_open2(struct svc_rqst *rqs
}
goto upgrade_out;
}
- mutex_lock(&stp->st_mutex);
status = nfs4_get_vfs_file(rqstp, fp, current_fh, stp, open);
if (status) {
mutex_unlock(&stp->st_mutex);
Patches currently in stable-queue which might be from green@xxxxxxxxxxxxxx are
queue-4.4/nfsd-always-lock-state-exclusively.patch
queue-4.4/nfsd-extend-the-mutex-holding-region-around-in-nfsd4_process_open2.patch
queue-4.4/make-nfs_atomic_open-call-d_drop-on-all-open_context-errors.patch
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