d/freebsd-skq
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

vfs: add support for WANTPARENT and LOCKPARENT to lockless lookup

Browse Source 
This makes the realpath syscall operational with the new lookup. Note that the
walk to obtain the full path name still takes locks.

Tested by:      pho
Differential Revision:	https://reviews.freebsd.org/D23917
This commit is contained in:
Mateusz Guzik 2020-07-30 15:45:11 +00:00
parent 8230d29357
commit 404927357d
1 changed files with 106 additions and 23 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

129
sys/kern/vfs_cache.c
View File

@ -3011,8 +3011,8 @@ cache_fpl_handled_impl(struct cache_fpl *fpl, int error, int line)
#define cache_fpl_handled(x, e) cache_fpl_handled_impl((x), (e), __LINE__)
#define CACHE_FPL_SUPPORTED_CN_FLAGS \
(LOCKLEAF | FOLLOW | LOCKSHARED | SAVENAME | ISOPEN | NOMACCHECK | \
AUDITVNODE1 | AUDITVNODE2)
(LOCKLEAF | LOCKPARENT | WANTPARENT | FOLLOW | LOCKSHARED | SAVENAME | \
ISOPEN | NOMACCHECK | AUDITVNODE1 | AUDITVNODE2)
static bool
cache_can_fplookup(struct cache_fpl *fpl)
@ -3208,35 +3208,17 @@ cache_fplookup_partial_setup(struct cache_fpl *fpl)
}
static int
cache_fplookup_final(struct cache_fpl *fpl)
cache_fplookup_final_child(struct cache_fpl *fpl, enum vgetstate tvs)
{
struct componentname *cnp;
enum vgetstate tvs;
struct vnode *dvp, *tvp;
seqc_t dvp_seqc, tvp_seqc;
struct vnode *tvp;
seqc_t tvp_seqc;
int error;
cnp = fpl->cnp;
dvp = fpl->dvp;
dvp_seqc = fpl->dvp_seqc;
tvp = fpl->tvp;
tvp_seqc = fpl->tvp_seqc;
VNPASS(cache_fplookup_vnode_supported(dvp), dvp);
tvs = vget_prep_smr(tvp);
if (tvs == VGET_NONE) {
return (cache_fpl_partial(fpl));
}
if (!vn_seqc_consistent(dvp, dvp_seqc)) {
cache_fpl_smr_exit(fpl);
vget_abort(tvp, tvs);
return (cache_fpl_aborted(fpl));
}
cache_fpl_smr_exit(fpl);
if ((cnp->cn_flags & LOCKLEAF) != 0) {
error = vget_finish(tvp, cnp->cn_lkflags, tvs);
if (error != 0) {
@ -3257,6 +3239,107 @@ cache_fplookup_final(struct cache_fpl *fpl)
return (cache_fpl_handled(fpl, 0));
}
static int __noinline
cache_fplookup_final_withparent(struct cache_fpl *fpl)
{
enum vgetstate dvs, tvs;
struct componentname *cnp;
struct vnode *dvp, *tvp;
seqc_t dvp_seqc, tvp_seqc;
int error;
cnp = fpl->cnp;
dvp = fpl->dvp;
dvp_seqc = fpl->dvp_seqc;
tvp = fpl->tvp;
tvp_seqc = fpl->tvp_seqc;
MPASS((cnp->cn_flags & (LOCKPARENT|WANTPARENT)) != 0);
/*
* This is less efficient than it can be for simplicity.
*/
dvs = vget_prep_smr(dvp);
if (dvs == VGET_NONE) {
return (cache_fpl_aborted(fpl));
}
tvs = vget_prep_smr(tvp);
if (tvs == VGET_NONE) {
cache_fpl_smr_exit(fpl);
vget_abort(dvp, dvs);
return (cache_fpl_aborted(fpl));
}
cache_fpl_smr_exit(fpl);
if ((cnp->cn_flags & LOCKPARENT) != 0) {
error = vget_finish(dvp, LK_EXCLUSIVE, dvs);
if (error != 0) {
vget_abort(tvp, tvs);
return (cache_fpl_aborted(fpl));
}
} else {
vget_finish_ref(dvp, dvs);
}
if (!vn_seqc_consistent(dvp, dvp_seqc)) {
vget_abort(tvp, tvs);
if ((cnp->cn_flags & LOCKPARENT) != 0)
vput(dvp);
else
vrele(dvp);
cache_fpl_aborted(fpl);
return (error);
}
error = cache_fplookup_final_child(fpl, tvs);
if (error != 0) {
MPASS(fpl->status == CACHE_FPL_STATUS_ABORTED);
if ((cnp->cn_flags & LOCKPARENT) != 0)
vput(dvp);
else
vrele(dvp);
return (error);
}
MPASS(fpl->status == CACHE_FPL_STATUS_HANDLED);
return (0);
}
static int
cache_fplookup_final(struct cache_fpl *fpl)
{
struct componentname *cnp;
enum vgetstate tvs;
struct vnode *dvp, *tvp;
seqc_t dvp_seqc, tvp_seqc;
cnp = fpl->cnp;
dvp = fpl->dvp;
dvp_seqc = fpl->dvp_seqc;
tvp = fpl->tvp;
tvp_seqc = fpl->tvp_seqc;
VNPASS(cache_fplookup_vnode_supported(dvp), dvp);
if ((cnp->cn_flags & (LOCKPARENT|WANTPARENT)) != 0)
return (cache_fplookup_final_withparent(fpl));
tvs = vget_prep_smr(tvp);
if (tvs == VGET_NONE) {
return (cache_fpl_partial(fpl));
}
if (!vn_seqc_consistent(dvp, dvp_seqc)) {
cache_fpl_smr_exit(fpl);
vget_abort(tvp, tvs);
return (cache_fpl_aborted(fpl));
}
cache_fpl_smr_exit(fpl);
return (cache_fplookup_final_child(fpl, tvs));
}
static int
cache_fplookup_next(struct cache_fpl *fpl)
{