Author: mjg
Date: Mon Aug 10 10:36:43 2020
New Revision: 364069
URL: https://svnweb.freebsd.org/changeset/base/364069
Log:
devfs: save on spurious relocking for devfs_populate
Tested by: pho
Modified:
head/sys/fs/devfs/devfs.h
head/sys/fs/devfs/devfs_devs.c
head/sys/fs/devfs/devfs_vnops.c
Modified: head/sys/fs/devfs/devfs.h
==============================================================================
--- head/sys/fs/devfs/devfs.h Mon Aug 10 10:36:10 2020 (r364068)
+++ head/sys/fs/devfs/devfs.h Mon Aug 10 10:36:43 2020 (r364069)
@@ -192,6 +192,7 @@ char *devfs_fqpn(char *, struct devfs_mount *,
struct
struct componentname *);
void devfs_delete(struct devfs_mount *, struct devfs_dirent *, int);
void devfs_dirent_free(struct devfs_dirent *);
+bool devfs_populate_needed(struct devfs_mount *dm);
void devfs_populate(struct devfs_mount *);
void devfs_cleanup(struct devfs_mount *);
void devfs_unmount_final(struct devfs_mount *);
Modified: head/sys/fs/devfs/devfs_devs.c
==============================================================================
--- head/sys/fs/devfs/devfs_devs.c Mon Aug 10 10:36:10 2020
(r364068)
+++ head/sys/fs/devfs/devfs_devs.c Mon Aug 10 10:36:43 2020
(r364069)
@@ -659,6 +659,13 @@ devfs_populate_loop(struct devfs_mount *dm, int cleanu
return (0);
}
+bool
+devfs_populate_needed(struct devfs_mount *dm)
+{
+
+ return (dm->dm_generation != devfs_generation);
+}
+
/*
* The caller needs to hold the dm for the duration of the call.
*/
@@ -668,9 +675,9 @@ devfs_populate(struct devfs_mount *dm)
unsigned gen;
sx_assert(&dm->dm_lock, SX_XLOCKED);
- gen = devfs_generation;
- if (dm->dm_generation == gen)
+ if (!devfs_populate_needed(dm))
return;
+ gen = devfs_generation;
while (devfs_populate_loop(dm, 0))
continue;
dm->dm_generation = gen;
Modified: head/sys/fs/devfs/devfs_vnops.c
==============================================================================
--- head/sys/fs/devfs/devfs_vnops.c Mon Aug 10 10:36:10 2020
(r364068)
+++ head/sys/fs/devfs/devfs_vnops.c Mon Aug 10 10:36:43 2020
(r364069)
@@ -235,6 +235,11 @@ devfs_populate_vp(struct vnode *vp)
ASSERT_VOP_LOCKED(vp, "devfs_populate_vp");
dmp = VFSTODEVFS(vp->v_mount);
+ if (!devfs_populate_needed(dmp)) {
+ sx_xlock(&dmp->dm_lock);
+ goto out_nopopulate;
+ }
+
locked = VOP_ISLOCKED(vp);
sx_xlock(&dmp->dm_lock);
@@ -252,6 +257,7 @@ devfs_populate_vp(struct vnode *vp)
devfs_unmount_final(dmp);
return (ERESTART);
}
+out_nopopulate:
if (VN_IS_DOOMED(vp)) {
sx_xunlock(&dmp->dm_lock);
return (ERESTART);
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