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nfsd: Extend the mutex holding region around in nfsd4_process_open2()

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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@linuxhacker.ru>
Cc: stable@vger.kernel.org
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
This commit is contained in:
Oleg Drokin 2016-06-14 23:28:05 -04:00 committed by J. Bruce Fields
parent feb9dad520
commit 5cc1fb2a09
1 changed files with 13 additions and 3 deletions
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16
fs/nfsd/nfs4state.c
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@ -3487,6 +3487,10 @@ init_open_stateid(struct nfs4_ol_stateid *stp, struct nfs4_file *fp,
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);
@ -3502,13 +3506,17 @@ init_open_stateid(struct nfs4_ol_stateid *stp, struct nfs4_file *fp,
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;
}
@ -4344,11 +4352,14 @@ nfsd4_process_open2(struct svc_rqst *rqstp, struct svc_fh *current_fh, struct nf
} 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) {
@ -4357,7 +4368,6 @@ nfsd4_process_open2(struct svc_rqst *rqstp, struct svc_fh *current_fh, struct nf
}
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);