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reduce duplicate code in path resolution
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@shivankgarg98
shivankgarg98 committed Aug 20, 2020
1 parent 79e5051 commit 418c1c2
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Showing 2 changed files with 13 additions and 124 deletions.
135 changes: 13 additions & 122 deletions sys/kern/vfs_cache.c
View file
Expand Up @@ -457,11 +457,8 @@ static int vn_fullpath_any(struct thread *td, struct vnode *vp, struct vnode *rd
char *buf, char **retbuf, size_t *buflen);
static int vn_fullpath_dir(struct thread *td, struct vnode *vp, struct vnode *rdir,
char *buf, char **retbuf, size_t *len, bool slash_prefixed, size_t addend);
static int vn_locked_fullpath_any(struct thread *td, struct vnode *vp,
static int vn_fullpath_any_locked(struct thread *td, struct vnode *vp,
struct vnode *rdir, char *buf, char **retbuf, size_t *buflen);
static int vn_locked_fullpath_dir(struct thread *td, struct vnode *vp,
struct vnode *rdir, char *buf, char **retbuf, size_t *len,
bool slash_prefixed, size_t addend);

static MALLOC_DEFINE(M_VFSCACHE, "vfscache", "VFS name cache entries");

Expand Down Expand Up @@ -2403,7 +2400,7 @@ vn_fullpath_global(struct thread *td, struct vnode *vn,
* LK_EXCLOTHER. Same doubt for everywhere I added VOP_ISLOCKED.
*/
if (lktype)
error = vn_locked_fullpath_any(td, vn, rootvnode, buf, retbuf,
error = vn_fullpath_any_locked(td, vn, rootvnode, buf, retbuf,
&buflen);
else
error = vn_fullpath_any(td, vn, rootvnode, buf, retbuf,
Expand Down Expand Up @@ -2480,8 +2477,8 @@ vn_vptocnp(struct vnode **vp, struct ucred *cred, char *buf, size_t *buflen)
/*
* The function works same as vn_vptocnp but for locked *vp.
*/
int
vn_locked_vptocnp(struct vnode **vp, struct ucred *cred, char *buf, size_t *buflen)
static int
vn_vptocnp_locked(struct vnode **vp, struct ucred *cred, char *buf, size_t *buflen)
{
struct vnode *dvp;
struct namecache *ncp;
Expand Down Expand Up @@ -2519,7 +2516,7 @@ vn_locked_vptocnp(struct vnode **vp, struct ucred *cred, char *buf, size_t *bufl

mtx_unlock(vlp);
KASSERT(VOP_ISLOCKED(*vp) != 0,
("vn_locked_vptocnp: vnode not locked"));
("vn_vptocnp_locked: vnode not locked"));
error = VOP_VPTOCNP(*vp, &dvp, cred, buf, buflen);
vunref(*vp);
if (error) {
Expand Down Expand Up @@ -2562,6 +2559,7 @@ vn_fullpath_dir(struct thread *td, struct vnode *vp, struct vnode *rdir,
struct vnode *vp1;
size_t buflen;
int error;
bool islocked;

VNPASS(vp->v_type == VDIR || VN_IS_DOOMED(vp), vp);
VNPASS(vp->v_usecount > 0, vp);
Expand All @@ -2578,113 +2576,7 @@ vn_fullpath_dir(struct thread *td, struct vnode *vp, struct vnode *rdir,

SDT_PROBE1(vfs, namecache, fullpath, entry, vp);
counter_u64_add(numfullpathcalls, 1);
while (vp != rdir && vp != rootvnode) {
/*
* The vp vnode must be already fully constructed,
* since it is either found in namecache or obtained
* from VOP_VPTOCNP(). We may test for VV_ROOT safely
* without obtaining the vnode lock.
*/
if ((vp->v_vflag & VV_ROOT) != 0) {
vn_lock(vp, LK_RETRY | LK_SHARED);

/*
* With the vnode locked, check for races with
* unmount, forced or not. Note that we
* already verified that vp is not equal to
* the root vnode, which means that
* mnt_vnodecovered can be NULL only for the
* case of unmount.
*/
if (VN_IS_DOOMED(vp) ||
(vp1 = vp->v_mount->mnt_vnodecovered) == NULL ||
vp1->v_mountedhere != vp->v_mount) {
vput(vp);
error = ENOENT;
SDT_PROBE3(vfs, namecache, fullpath, return,
error, vp, NULL);
break;
}

vref(vp1);
vput(vp);
vp = vp1;
continue;
}
if (vp->v_type != VDIR) {
vrele(vp);
counter_u64_add(numfullpathfail1, 1);
error = ENOTDIR;
SDT_PROBE3(vfs, namecache, fullpath, return,
error, vp, NULL);
break;
}
error = vn_vptocnp(&vp, td->td_ucred, buf, &buflen);
if (error)
break;
if (buflen == 0) {
vrele(vp);
error = ENOMEM;
SDT_PROBE3(vfs, namecache, fullpath, return, error,
startvp, NULL);
break;
}
buf[--buflen] = '/';
slash_prefixed = true;
}
if (error)
return (error);
if (!slash_prefixed) {
if (buflen == 0) {
vrele(vp);
counter_u64_add(numfullpathfail4, 1);
SDT_PROBE3(vfs, namecache, fullpath, return, ENOMEM,
startvp, NULL);
return (ENOMEM);
}
buf[--buflen] = '/';
}
counter_u64_add(numfullpathfound, 1);
vrele(vp);

*retbuf = buf + buflen;
SDT_PROBE3(vfs, namecache, fullpath, return, 0, startvp, *retbuf);
*len -= buflen;
*len += addend;
return (0);
}

/*
* This function works same as vn_fullpath_dir but for locked vnode *vp.
*/
static int
vn_locked_fullpath_dir(struct thread *td, struct vnode *vp, struct vnode *rdir,
char *buf, char **retbuf, size_t *len, bool slash_prefixed, size_t addend)
{
#ifdef KDTRACE_HOOKS
struct vnode *startvp = vp;
#endif
struct vnode *vp1;
size_t buflen;
int error;
bool islocked = true;

VNPASS(vp->v_type == VDIR || VN_IS_DOOMED(vp), vp);
VNPASS(vp->v_usecount > 0, vp);
KASSERT(VOP_ISLOCKED(vp) != 0,
("vn_locked_fullpath_dir: vp not locked"));
buflen = *len;

if (!slash_prefixed) {
MPASS(*len >= 2);
buflen--;
buf[buflen] = '\0';
}

error = 0;

SDT_PROBE1(vfs, namecache, fullpath, entry, vp);
counter_u64_add(numfullpathcalls, 1);
islocked = (VOP_ISLOCKED(vp)) ? true : false;
while (vp != rdir && vp != rootvnode) {
/*
* The vp vnode must be already fully constructed,
Expand Down Expand Up @@ -2741,7 +2633,7 @@ vn_locked_fullpath_dir(struct thread *td, struct vnode *vp, struct vnode *rdir,
if (!islocked)
error = vn_vptocnp(&vp, td->td_ucred, buf, &buflen);
else
error = vn_locked_vptocnp(&vp, td->td_ucred, buf,
error = vn_vptocnp_locked(&vp, td->td_ucred, buf,
&buflen);
islocked = (VOP_ISLOCKED(vp)) ? true : false;
if (error)
Expand Down Expand Up @@ -2786,6 +2678,7 @@ vn_locked_fullpath_dir(struct thread *td, struct vnode *vp, struct vnode *rdir,
*len += addend;
return (0);
}

/*
* Resolve an arbitrary vnode to a pathname.
*
Expand Down Expand Up @@ -2833,7 +2726,7 @@ vn_fullpath_any(struct thread *td, struct vnode *vp, struct vnode *rdir,
* This function works same as vn_fullpath_any but for locked vnode.
*/
static int
vn_locked_fullpath_any(struct thread *td, struct vnode *vp, struct vnode *rdir,
vn_fullpath_any_locked(struct thread *td, struct vnode *vp, struct vnode *rdir,
char *buf, char **retbuf, size_t *buflen)
{
size_t orig_buflen;
Expand All @@ -2844,12 +2737,13 @@ vn_locked_fullpath_any(struct thread *td, struct vnode *vp, struct vnode *rdir,
return (EINVAL);

orig_buflen = *buflen;

vref(vp);
slash_prefixed = false;
if (vp->v_type != VDIR) {
*buflen -= 1;
buf[*buflen] = '\0';
error = vn_locked_vptocnp(&vp, td->td_ucred, buf, buflen);
error = vn_vptocnp_locked(&vp, td->td_ucred, buf, buflen);
if (error)
return (error);
lktype = VOP_ISLOCKED(vp);
Expand All @@ -2863,12 +2757,9 @@ vn_locked_fullpath_any(struct thread *td, struct vnode *vp, struct vnode *rdir,
*buflen -= 1;
buf[*buflen] = '/';
slash_prefixed = true;
if (lktype == 0)
return (vn_fullpath_dir(td, vp, rdir, buf, retbuf,
buflen, slash_prefixed, orig_buflen - *buflen));
}

return (vn_locked_fullpath_dir(td, vp, rdir, buf, retbuf, buflen,
return (vn_fullpath_dir(td, vp, rdir, buf, retbuf, buflen,
slash_prefixed, orig_buflen - *buflen));
}
/*
Expand Down
2 changes: 0 additions & 2 deletions sys/sys/vnode.h
View file
Expand Up @@ -653,8 +653,6 @@ u_quad_t init_va_filerev(void);
int speedup_syncer(void);
int vn_vptocnp(struct vnode **vp, struct ucred *cred, char *buf,
size_t *buflen);
int vn_locked_vptocnp(struct vnode **vp, struct ucred *cred, char *buf,
size_t *buflen);
int vn_getcwd(struct thread *td, char *buf, char **retbuf, size_t *buflen);
int vn_fullpath(struct thread *td, struct vnode *vn,
char **retbuf, char **freebuf);
Expand Down

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