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lockd: don't attempt blocking locks on nfs reexports

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As in the v4 case, it doesn't work well to block waiting for a lock on
an nfs filesystem.

As in the v4 case, that means we're depending on the client to poll.
It's probably incorrect to depend on that, but I *think* clients do poll
in practice.  In any case, it's an improvement over hanging the lockd
thread indefinitely as we currently are.

Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Acked-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
This commit is contained in:
J. Bruce Fields 2021-08-20 17:02:05 -04:00 committed by Chuck Lever
parent f657f8eef3
commit b840be2f00
1 changed files with 10 additions and 3 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

13
fs/lockd/svclock.c
View file

@ -31,6 +31,7 @@
#include <linux/lockd/nlm.h>
#include <linux/lockd/lockd.h>
#include <linux/kthread.h>
#include <linux/exportfs.h>
#define NLMDBG_FACILITY NLMDBG_SVCLOCK
@ -470,18 +471,24 @@ nlmsvc_lock(struct svc_rqst *rqstp, struct nlm_file *file,
struct nlm_cookie *cookie, int reclaim)
{
struct nlm_block *block = NULL;
struct inode *inode = nlmsvc_file_inode(file);
int error;
int mode;
int async_block = 0;
__be32 ret;
dprintk("lockd: nlmsvc_lock(%s/%ld, ty=%d, pi=%d, %Ld-%Ld, bl=%d)\n",
nlmsvc_file_inode(file)->i_sb->s_id,
nlmsvc_file_inode(file)->i_ino,
inode->i_sb->s_id, inode->i_ino,
lock->fl.fl_type, lock->fl.fl_pid,
(long long)lock->fl.fl_start,
(long long)lock->fl.fl_end,
wait);
if (inode->i_sb->s_export_op->flags & EXPORT_OP_SYNC_LOCKS) {
async_block = wait;
wait = 0;
}
/* Lock file against concurrent access */
mutex_lock(&file->f_mutex);
/* Get existing block (in case client is busy-waiting)
@ -542,7 +549,7 @@ nlmsvc_lock(struct svc_rqst *rqstp, struct nlm_file *file,
*/
if (wait)
break;
ret = nlm_lck_denied;
ret = async_block ? nlm_lck_blocked : nlm_lck_denied;
goto out;
case FILE_LOCK_DEFERRED:
if (wait)