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vfs: replace the MNTK_TEXT_REFS flag with VIRF_TEXT_REF

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This allows to stop maintaing the VI_TEXT_REF flag and consequently
opens up fully lockless v_writecount adjustment.

Reviewed by:	kib
Differential Revision:	https://reviews.freebsd.org/D33127
This commit is contained in:
Mateusz Guzik 2021-05-18 12:47:21 +02:00
parent 1c15c8c0e9
commit 4dcdf3987c
6 changed files with 18 additions and 19 deletions
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2
sys/fs/tmpfs/tmpfs_subr.c
View File

@ -967,7 +967,7 @@ tmpfs_alloc_vp(struct mount *mp, struct tmpfs_node *node, int lkflag,
vp->v_object = object;
object->un_pager.swp.swp_tmpfs = vp;
vm_object_set_flag(object, OBJ_TMPFS);
vn_irflag_set_locked(vp, VIRF_PGREAD);
vn_irflag_set_locked(vp, VIRF_PGREAD | VIRF_TEXT_REF);
VI_UNLOCK(vp);
VM_OBJECT_WUNLOCK(object);
break;

2
sys/fs/tmpfs/tmpfs_vfsops.c
View File

@ -469,7 +469,7 @@ tmpfs_mount(struct mount *mp)
MNT_ILOCK(mp);
mp->mnt_flag |= MNT_LOCAL;
mp->mnt_kern_flag |= MNTK_LOOKUP_SHARED | MNTK_EXTENDED_SHARED |
MNTK_TEXT_REFS | MNTK_NOMSYNC;
MNTK_NOMSYNC;
if (!nonc && (mp->mnt_flag & MNT_UNION) == 0)
mp->mnt_kern_flag |= MNTK_FPLOOKUP;
MNT_IUNLOCK(mp);

20
sys/kern/vfs_default.c
View File

@ -1300,7 +1300,6 @@ int
vop_stdset_text(struct vop_set_text_args *ap)
{
struct vnode *vp;
struct mount *mp;
int error, n;
vp = ap->a_vp;
@ -1326,12 +1325,10 @@ vop_stdset_text(struct vop_set_text_args *ap)
* If requested by fs, keep a use reference to the
* vnode until the last text reference is released.
*/
mp = vp->v_mount;
if (mp != NULL && (mp->mnt_kern_flag & MNTK_TEXT_REFS) != 0 &&
vp->v_writecount == 0) {
VNPASS((vp->v_iflag & VI_TEXT_REF) == 0, vp);
vp->v_iflag |= VI_TEXT_REF;
vrefl(vp);
if ((vn_irflag_read(vp) & VIRF_TEXT_REF) != 0) {
if (vp->v_writecount == 0) {
vrefl(vp);
}
}
atomic_subtract_int(&vp->v_writecount, 1);
@ -1366,11 +1363,12 @@ vop_stdunset_text(struct vop_unset_text_args *ap)
last = false;
VI_LOCK(vp);
if (vp->v_writecount < 0) {
if ((vp->v_iflag & VI_TEXT_REF) != 0 &&
vp->v_writecount == -1) {
last = true;
vp->v_iflag &= ~VI_TEXT_REF;
if ((vn_irflag_read(vp) & VIRF_TEXT_REF) != 0) {
if (vp->v_writecount == -1) {
last = true;
}
}
atomic_add_int(&vp->v_writecount, 1);
error = 0;
} else {

8
sys/kern/vfs_subr.c
View File

@ -4122,7 +4122,9 @@ vn_printf(struct vnode *vp, const char *fmt, ...)
strlcat(buf, "|VIRF_PGREAD", sizeof(buf));
if (irflag & VIRF_MOUNTPOINT)
strlcat(buf, "|VIRF_MOUNTPOINT", sizeof(buf));
flags = irflag & ~(VIRF_DOOMED | VIRF_PGREAD | VIRF_MOUNTPOINT);
if (irflag & VIRF_TEXT_REF)
strlcat(buf, "|VIRF_TEXT_REF", sizeof(buf));
flags = irflag & ~(VIRF_DOOMED | VIRF_PGREAD | VIRF_MOUNTPOINT | VIRF_TEXT_REF);
if (flags != 0) {
snprintf(buf2, sizeof(buf2), "|VIRF(0x%lx)", flags);
strlcat(buf, buf2, sizeof(buf));
@ -4163,8 +4165,6 @@ vn_printf(struct vnode *vp, const char *fmt, ...)
snprintf(buf2, sizeof(buf2), "|VV(0x%lx)", flags);
strlcat(buf, buf2, sizeof(buf));
}
if (vp->v_iflag & VI_TEXT_REF)
strlcat(buf, "|VI_TEXT_REF", sizeof(buf));
if (vp->v_iflag & VI_MOUNT)
strlcat(buf, "|VI_MOUNT", sizeof(buf));
if (vp->v_iflag & VI_DOINGINACT)
@ -4175,7 +4175,7 @@ vn_printf(struct vnode *vp, const char *fmt, ...)
strlcat(buf, "|VI_DEFINACT", sizeof(buf));
if (vp->v_iflag & VI_FOPENING)
strlcat(buf, "|VI_FOPENING", sizeof(buf));
flags = vp->v_iflag & ~(VI_TEXT_REF | VI_MOUNT | VI_DOINGINACT |
flags = vp->v_iflag & ~(VI_MOUNT | VI_DOINGINACT |
VI_OWEINACT | VI_DEFINACT | VI_FOPENING);
if (flags != 0) {
snprintf(buf2, sizeof(buf2), "|VI(0x%lx)", flags);

2
sys/sys/mount.h
View File

@ -489,7 +489,7 @@ struct mntoptnames {
#define MNTK_LOOKUP_EXCL_DOTDOT 0x00000800
#define MNTK_UNMAPPED_BUFS 0x00002000
#define MNTK_USES_BCACHE 0x00004000 /* FS uses the buffer cache. */
#define MNTK_TEXT_REFS 0x00008000 /* Keep use ref for text */
#define MNTK_UNUSED0 0x00008000 /* unused */
#define MNTK_VMSETSIZE_BUG 0x00010000
#define MNTK_UNIONFS 0x00020000 /* A hack for F_ISUNIONSTACK */
#define MNTK_FPLOOKUP 0x00040000 /* fast path lookup is supported */

3
sys/sys/vnode.h
View File

@ -251,8 +251,9 @@ struct xvnode {
#define VIRF_PGREAD 0x0002 /* Direct reads from the page cache are permitted,
never cleared once set */
#define VIRF_MOUNTPOINT 0x0004 /* This vnode is mounted on */
#define VIRF_TEXT_REF 0x0008 /* Executable mappings ref the vnode */
#define VI_TEXT_REF 0x0001 /* Text ref grabbed use ref */
#define VI_UNUSED0 0x0001 /* unused */
#define VI_MOUNT 0x0002 /* Mount in progress */
#define VI_DOINGINACT 0x0004 /* VOP_INACTIVE is in progress */
#define VI_OWEINACT 0x0008 /* Need to call inactive */