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authorJeff Layton <jlayton@kernel.org>2019-04-29 12:13:14 -0400
committerIlya Dryomov <idryomov@gmail.com>2019-05-07 19:22:37 +0200
commitf77f21bb28367d0ac4861a24da1db118bba850e6 (patch)
tree09381ee5d6fac1e444a8795da70eb08fe4ce551d /fs/ceph
parent964fff7491e4923e18ff08f2a254c4b94e3f83d6 (diff)
downloadlinux-f77f21bb28367d0ac4861a24da1db118bba850e6.tar.bz2
ceph: use __getname/__putname in ceph_mdsc_build_path
Al suggested we get rid of the kmalloc here and just use __getname and __putname to get a full PATH_MAX pathname buffer. Since we build the path in reverse, we continue to return a pointer to the beginning of the string and the length, and add a new helper to free the thing at the end. Suggested-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Jeff Layton <jlayton@kernel.org> Reviewed-by: "Yan, Zheng" <zyan@redhat.com> Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Diffstat (limited to 'fs/ceph')
-rw-r--r--fs/ceph/debugfs.c4
-rw-r--r--fs/ceph/mds_client.c65
-rw-r--r--fs/ceph/mds_client.h6
3 files changed, 36 insertions, 39 deletions
diff --git a/fs/ceph/debugfs.c b/fs/ceph/debugfs.c
index 777f6ceb5259..b014fc7d4e3c 100644
--- a/fs/ceph/debugfs.c
+++ b/fs/ceph/debugfs.c
@@ -88,7 +88,7 @@ static int mdsc_show(struct seq_file *s, void *p)
req->r_dentry,
path ? path : "");
spin_unlock(&req->r_dentry->d_lock);
- kfree(path);
+ ceph_mdsc_free_path(path, pathlen);
} else if (req->r_path1) {
seq_printf(s, " #%llx/%s", req->r_ino1.ino,
req->r_path1);
@@ -108,7 +108,7 @@ static int mdsc_show(struct seq_file *s, void *p)
req->r_old_dentry,
path ? path : "");
spin_unlock(&req->r_old_dentry->d_lock);
- kfree(path);
+ ceph_mdsc_free_path(path, pathlen);
} else if (req->r_path2 && req->r_op != CEPH_MDS_OP_SYMLINK) {
if (req->r_ino2.ino)
seq_printf(s, " #%llx/%s", req->r_ino2.ino,
diff --git a/fs/ceph/mds_client.c b/fs/ceph/mds_client.c
index 7af722834348..d29f6c094f7c 100644
--- a/fs/ceph/mds_client.c
+++ b/fs/ceph/mds_client.c
@@ -2094,39 +2094,24 @@ char *ceph_mdsc_build_path(struct dentry *dentry, int *plen, u64 *pbase,
{
struct dentry *temp;
char *path;
- int len, pos;
+ int pos;
unsigned seq;
u64 base;
if (!dentry)
return ERR_PTR(-EINVAL);
-retry:
- len = 0;
- seq = read_seqbegin(&rename_lock);
- rcu_read_lock();
- for (temp = dentry; !IS_ROOT(temp);) {
- struct inode *inode = d_inode(temp);
- if (inode && ceph_snap(inode) == CEPH_SNAPDIR)
- len++; /* slash only */
- else if (stop_on_nosnap && inode &&
- ceph_snap(inode) == CEPH_NOSNAP)
- break;
- else
- len += 1 + temp->d_name.len;
- temp = temp->d_parent;
- }
- rcu_read_unlock();
- if (len)
- len--; /* no leading '/' */
-
- path = kmalloc(len+1, GFP_NOFS);
+ path = __getname();
if (!path)
return ERR_PTR(-ENOMEM);
- pos = len;
- path[pos] = 0; /* trailing null */
+retry:
+ pos = PATH_MAX - 1;
+ path[pos] = '\0';
+
+ seq = read_seqbegin(&rename_lock);
rcu_read_lock();
- for (temp = dentry; !IS_ROOT(temp) && pos != 0; ) {
+ temp = dentry;
+ for (;;) {
struct inode *inode;
spin_lock(&temp->d_lock);
@@ -2144,32 +2129,38 @@ retry:
spin_unlock(&temp->d_lock);
break;
}
- strncpy(path + pos, temp->d_name.name,
- temp->d_name.len);
+ memcpy(path + pos, temp->d_name.name, temp->d_name.len);
}
spin_unlock(&temp->d_lock);
- if (pos)
- path[--pos] = '/';
temp = temp->d_parent;
+
+ /* Are we at the root? */
+ if (IS_ROOT(temp))
+ break;
+
+ /* Are we out of buffer? */
+ if (--pos < 0)
+ break;
+
+ path[pos] = '/';
}
base = ceph_ino(d_inode(temp));
rcu_read_unlock();
- if (pos != 0 || read_seqretry(&rename_lock, seq)) {
+ if (pos < 0 || read_seqretry(&rename_lock, seq)) {
pr_err("build_path did not end path lookup where "
- "expected, namelen is %d, pos is %d\n", len, pos);
+ "expected, pos is %d\n", pos);
/* presumably this is only possible if racing with a
rename of one of the parent directories (we can not
lock the dentries above us to prevent this, but
retrying should be harmless) */
- kfree(path);
goto retry;
}
*pbase = base;
- *plen = len;
+ *plen = PATH_MAX - 1 - pos;
dout("build_path on %p %d built %llx '%.*s'\n",
- dentry, d_count(dentry), base, len, path);
- return path;
+ dentry, d_count(dentry), base, *plen, path + pos);
+ return path + pos;
}
static int build_dentry_path(struct dentry *dentry, struct inode *dir,
@@ -2376,10 +2367,10 @@ static struct ceph_msg *create_request_message(struct ceph_mds_client *mdsc,
out_free2:
if (freepath2)
- kfree((char *)path2);
+ ceph_mdsc_free_path((char *)path2, pathlen2);
out_free1:
if (freepath1)
- kfree((char *)path1);
+ ceph_mdsc_free_path((char *)path1, pathlen1);
out:
return msg;
}
@@ -3451,7 +3442,7 @@ out_freeflocks:
ceph_pagelist_encode_string(pagelist, path, pathlen);
ceph_pagelist_append(pagelist, &rec, sizeof(rec.v1));
out_freepath:
- kfree(path);
+ ceph_mdsc_free_path(path, pathlen);
}
out_err:
diff --git a/fs/ceph/mds_client.h b/fs/ceph/mds_client.h
index 0d1f673a5689..ebcad5afc87b 100644
--- a/fs/ceph/mds_client.h
+++ b/fs/ceph/mds_client.h
@@ -492,6 +492,12 @@ extern int ceph_iterate_session_caps(struct ceph_mds_session *session,
void *arg);
extern void ceph_mdsc_pre_umount(struct ceph_mds_client *mdsc);
+static inline void ceph_mdsc_free_path(char *path, int len)
+{
+ if (path)
+ __putname(path - (PATH_MAX - 1 - len));
+}
+
extern char *ceph_mdsc_build_path(struct dentry *dentry, int *plen, u64 *base,
int stop_on_nosnap);