Commit df91b9df authored by Oleg Nesterov's avatar Oleg Nesterov Committed by David Howells
Browse files

afs: use read_seqbegin() in afs_check_validity() and afs_getattr() 



David Howells says:

 (3) afs_check_validity().
 (4) afs_getattr().

     These are both pretty short, so your solution is probably good for them.
     That said, afs_vnode_commit_status() can spend a long time under the
     write lock - and pretty much every file RPC op returns a status update.

Change these functions to use read_seqbegin(). This simplifies the code
and doesn't change the current behaviour, the "seq" counter is always even
so read_seqbegin_or_lock() can never take the lock.

Signed-off-by: default avatarOleg Nesterov <oleg@redhat.com>
Signed-off-by: default avatarDavid Howells <dhowells@redhat.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org
Link: https://lore.kernel.org/r/20231130115617.GA21584@redhat.com/
parent 1702e065

fs/afs/inode.c

+6 −9
Original line number Diff line number Diff line
@@ -629,10 +629,10 @@ bool afs_check_validity(struct afs_vnode *vnode) 
	enum afs_cb_break_reason need_clear = afs_cb_break_no_break;

	time64_t now = ktime_get_real_seconds();

	unsigned int cb_break;

	int seq = 0;

	int seq;



	do {

		read_seqbegin_or_lock(&vnode->cb_lock, &seq);

		seq = read_seqbegin(&vnode->cb_lock);

		cb_break = vnode->cb_break;



		if (test_bit(AFS_VNODE_CB_PROMISED, &vnode->flags)) {
@@ -650,9 +650,7 @@ bool afs_check_validity(struct afs_vnode *vnode) 
			need_clear = afs_cb_break_no_promise;

		}



	} while (need_seqretry(&vnode->cb_lock, seq));



	done_seqretry(&vnode->cb_lock, seq);

	} while (read_seqretry(&vnode->cb_lock, seq));



	if (need_clear == afs_cb_break_no_break)

		return true;
@@ -755,7 +753,7 @@ int afs_getattr(struct mnt_idmap *idmap, const struct path *path, 
	struct inode *inode = d_inode(path->dentry);

	struct afs_vnode *vnode = AFS_FS_I(inode);

	struct key *key;

	int ret, seq = 0;

	int ret, seq;



	_enter("{ ino=%lu v=%u }", inode->i_ino, inode->i_generation);
@@ -772,7 +770,7 @@ int afs_getattr(struct mnt_idmap *idmap, const struct path *path, 
	}



	do {

		read_seqbegin_or_lock(&vnode->cb_lock, &seq);

		seq = read_seqbegin(&vnode->cb_lock);

		generic_fillattr(&nop_mnt_idmap, request_mask, inode, stat);

		if (test_bit(AFS_VNODE_SILLY_DELETED, &vnode->flags) &&

		    stat->nlink > 0)
@@ -784,9 +782,8 @@ int afs_getattr(struct mnt_idmap *idmap, const struct path *path, 
		 */

		if (S_ISDIR(inode->i_mode))

			stat->size = vnode->netfs.remote_i_size;

	} while (need_seqretry(&vnode->cb_lock, seq));

	} while (read_seqretry(&vnode->cb_lock, seq));



	done_seqretry(&vnode->cb_lock, seq);

	return 0;

}