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Add V_MNTREF flag to the vn_start_write(9) and

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vn_start_secondary_write(9) functions.  The flag indicates that the
caller already owns a reference on the mount point, and the functions
can consume it.  The reference is released by vn_finished_write(9) and
vn_finished_secondary_write(9) in due course.

Tested by:	pho
Sponsored by:	The FreeBSD Foundation
MFC after:	2 weeks
This commit is contained in:
Konstantin Belousov 2015-05-27 09:21:47 +00:00
parent 1bc93bb7b9
commit 2db0e1f50d
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=283601
2 changed files with 17 additions and 12 deletions
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28
sys/kern/vfs_vnops.c
View File

@ -1646,16 +1646,18 @@ vn_start_write_locked(struct mount *mp, int flags)
}
int
vn_start_write(vp, mpp, flags)
struct vnode *vp;
struct mount **mpp;
int flags;
vn_start_write(struct vnode *vp, struct mount **mpp, int flags)
{
struct mount *mp;
int error;
if (!vn_suspendable(vp, mpp))
KASSERT((flags & V_MNTREF) == 0 || (*mpp != NULL && vp == NULL),
("V_MNTREF requires mp"));
if (!vn_suspendable(vp, mpp)) {
if ((flags & V_MNTREF) != 0)
vfs_rel(*mpp);
return (0);
}
error = 0;
/*
@ -1681,7 +1683,7 @@ vn_start_write(vp, mpp, flags)
* emulate a vfs_ref().
*/
MNT_ILOCK(mp);
if (vp == NULL)
if (vp == NULL && (flags & V_MNTREF) == 0)
MNT_REF(mp);
return (vn_start_write_locked(mp, flags));
@ -1695,16 +1697,18 @@ vn_start_write(vp, mpp, flags)
* time, these operations are halted until the suspension is over.
*/
int
vn_start_secondary_write(vp, mpp, flags)
struct vnode *vp;
struct mount **mpp;
int flags;
vn_start_secondary_write(struct vnode *vp, struct mount **mpp, int flags)
{
struct mount *mp;
int error;
if (!vn_suspendable(vp, mpp))
KASSERT((flags & V_MNTREF) == 0 || (*mpp != NULL && vp == NULL),
("V_MNTREF requires mp"));
if (!vn_suspendable(vp, mpp)) {
if ((flags & V_MNTREF) != 0)
vfs_rel(*mpp);
return (0);
}
retry:
if (vp != NULL) {
@ -1730,7 +1734,7 @@ vn_start_secondary_write(vp, mpp, flags)
* emulate a vfs_ref().
*/
MNT_ILOCK(mp);
if (vp == NULL)
if (vp == NULL && (flags & V_MNTREF) == 0)
MNT_REF(mp);
if ((mp->mnt_kern_flag & (MNTK_SUSPENDED | MNTK_SUSPEND2)) == 0) {
mp->mnt_secondary_writes++;

1
sys/sys/vnode.h
View File

@ -397,6 +397,7 @@ extern int vttoif_tab[];
#define V_WAIT 0x0001 /* vn_start_write: sleep for suspend */
#define V_NOWAIT 0x0002 /* vn_start_write: don't sleep for suspend */
#define V_XSLEEP 0x0004 /* vn_start_write: just return after sleep */
#define V_MNTREF 0x0010 /* vn_start_write: mp is already ref-ed */
#define VR_START_WRITE 0x0001 /* vfs_write_resume: start write atomically */
#define VR_NO_SUSPCLR 0x0002 /* vfs_write_resume: do not clear suspension */