Date: Wed, 27 May 2015 09:21:48 +0000 (UTC) From: Konstantin Belousov <kib@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r283601 - in head/sys: kern sys Message-ID: <201505270921.t4R9LmY0064978@svn.freebsd.org>
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Author: kib Date: Wed May 27 09:21:47 2015 New Revision: 283601 URL: https://svnweb.freebsd.org/changeset/base/283601 Log: Add V_MNTREF flag to the vn_start_write(9) and 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 Modified: head/sys/kern/vfs_vnops.c head/sys/sys/vnode.h Modified: head/sys/kern/vfs_vnops.c ============================================================================== --- head/sys/kern/vfs_vnops.c Wed May 27 09:20:42 2015 (r283600) +++ head/sys/kern/vfs_vnops.c Wed May 27 09:21:47 2015 (r283601) @@ -1646,16 +1646,18 @@ unlock: } 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++; Modified: head/sys/sys/vnode.h ============================================================================== --- head/sys/sys/vnode.h Wed May 27 09:20:42 2015 (r283600) +++ head/sys/sys/vnode.h Wed May 27 09:21:47 2015 (r283601) @@ -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 */
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