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ceph: cleanup splice_dentry()

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splice_dentry() may drop the original dentry and return other
dentry. It relies on its caller to update pointer that points
to the dropped dentry. This is error-prone.

Signed-off-by: "Yan, Zheng" <zyan@redhat.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
This commit is contained in:
Yan, Zheng 2018-10-25 17:30:30 +08:00 committed by Ilya Dryomov
parent 8fe28cb58b
commit 2bf996ac48
1 changed files with 24 additions and 36 deletions
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60
fs/ceph/inode.c
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@ -1098,8 +1098,9 @@ out_unlock:
* splice a dentry to an inode.
* caller must hold directory i_mutex for this to be safe.
*/
static struct dentry *splice_dentry(struct dentry *dn, struct inode *in)
static int splice_dentry(struct dentry **pdn, struct inode *in)
{
struct dentry *dn = *pdn;
struct dentry *realdn;
BUG_ON(d_inode(dn));
@ -1132,28 +1133,23 @@ static struct dentry *splice_dentry(struct dentry *dn, struct inode *in)
if (IS_ERR(realdn)) {
pr_err("splice_dentry error %ld %p inode %p ino %llx.%llx\n",
PTR_ERR(realdn), dn, in, ceph_vinop(in));
dn = realdn;
/*
* Caller should release 'dn' in the case of error.
* If 'req->r_dentry' is passed to this function,
* caller should leave 'req->r_dentry' untouched.
*/
goto out;
} else if (realdn) {
return PTR_ERR(realdn);
}
if (realdn) {
dout("dn %p (%d) spliced with %p (%d) "
"inode %p ino %llx.%llx\n",
dn, d_count(dn),
realdn, d_count(realdn),
d_inode(realdn), ceph_vinop(d_inode(realdn)));
dput(dn);
dn = realdn;
*pdn = realdn;
} else {
BUG_ON(!ceph_dentry(dn));
dout("dn %p attached to %p ino %llx.%llx\n",
dn, d_inode(dn), ceph_vinop(d_inode(dn)));
}
out:
return dn;
return 0;
}
/*
@ -1340,7 +1336,12 @@ retry_lookup:
dout("dn %p gets new offset %lld\n", req->r_old_dentry,
ceph_dentry(req->r_old_dentry)->offset);
dn = req->r_old_dentry; /* use old_dentry */
/* swap r_dentry and r_old_dentry in case that
* splice_dentry() gets called later. This is safe
* because no other place will use them */
req->r_dentry = req->r_old_dentry;
req->r_old_dentry = dn;
dn = req->r_dentry;
}
/* null dentry? */
@ -1365,12 +1366,10 @@ retry_lookup:
if (d_really_is_negative(dn)) {
ceph_dir_clear_ordered(dir);
ihold(in);
dn = splice_dentry(dn, in);
if (IS_ERR(dn)) {
err = PTR_ERR(dn);
err = splice_dentry(&req->r_dentry, in);
if (err < 0)
goto done;
}
req->r_dentry = dn; /* may have spliced */
dn = req->r_dentry; /* may have spliced */
} else if (d_really_is_positive(dn) && d_inode(dn) != in) {
dout(" %p links to %p %llx.%llx, not %llx.%llx\n",
dn, d_inode(dn), ceph_vinop(d_inode(dn)),
@ -1390,22 +1389,18 @@ retry_lookup:
} else if ((req->r_op == CEPH_MDS_OP_LOOKUPSNAP ||
req->r_op == CEPH_MDS_OP_MKSNAP) &&
!test_bit(CEPH_MDS_R_ABORTED, &req->r_req_flags)) {
struct dentry *dn = req->r_dentry;
struct inode *dir = req->r_parent;
/* fill out a snapdir LOOKUPSNAP dentry */
BUG_ON(!dn);
BUG_ON(!dir);
BUG_ON(ceph_snap(dir) != CEPH_SNAPDIR);
dout(" linking snapped dir %p to dn %p\n", in, dn);
BUG_ON(!req->r_dentry);
dout(" linking snapped dir %p to dn %p\n", in, req->r_dentry);
ceph_dir_clear_ordered(dir);
ihold(in);
dn = splice_dentry(dn, in);
if (IS_ERR(dn)) {
err = PTR_ERR(dn);
err = splice_dentry(&req->r_dentry, in);
if (err < 0)
goto done;
}
req->r_dentry = dn; /* may have spliced */
} else if (rinfo->head->is_dentry) {
struct ceph_vino *ptvino = NULL;
@ -1669,8 +1664,6 @@ retry_lookup:
}
if (d_really_is_negative(dn)) {
struct dentry *realdn;
if (ceph_security_xattr_deadlock(in)) {
dout(" skip splicing dn %p to inode %p"
" (security xattr deadlock)\n", dn, in);
@ -1679,13 +1672,9 @@ retry_lookup:
goto next_item;
}
realdn = splice_dentry(dn, in);
if (IS_ERR(realdn)) {
err = PTR_ERR(realdn);
d_drop(dn);
err = splice_dentry(&dn, in);
if (err < 0)
goto next_item;
}
dn = realdn;
}
ceph_dentry(dn)->offset = rde->offset;
@ -1701,8 +1690,7 @@ retry_lookup:
err = ret;
}
next_item:
if (dn)
dput(dn);
dput(dn);
}
out:
if (err == 0 && skipped == 0) {