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authorJeff Layton <jlayton@kernel.org>2020-08-05 20:50:48 +0200
committerIlya Dryomov <idryomov@gmail.com>2023-08-22 09:01:48 +0200
commit4c793d4c58b7e57e1eb616e3d032df6b3789a4a3 (patch)
tree9b5f56b8164ce25ecec56bc24ffdfdfa49b9790f /fs
parentceph: preallocate inode for ops that may create one (diff)
downloadlinux-4c793d4c58b7e57e1eb616e3d032df6b3789a4a3.tar.xz
linux-4c793d4c58b7e57e1eb616e3d032df6b3789a4a3.zip
ceph: make ceph_msdc_build_path use ref-walk
Encryption potentially requires allocation, at which point we'll need to be in a non-atomic context. Convert ceph_msdc_build_path to take dentry spinlocks and references instead of using rcu_read_lock to walk the path. This is slightly less efficient, and we may want to eventually allow using RCU when the leaf dentry isn't encrypted. Signed-off-by: Jeff Layton <jlayton@kernel.org> Reviewed-by: Xiubo Li <xiubli@redhat.com> Reviewed-and-tested-by: Luís Henriques <lhenriques@suse.de> Reviewed-by: Milind Changire <mchangir@redhat.com> Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Diffstat (limited to 'fs')
-rw-r--r--fs/ceph/mds_client.c35
1 files changed, 19 insertions, 16 deletions
diff --git a/fs/ceph/mds_client.c b/fs/ceph/mds_client.c
index 73dfea88bb88..77b5e7b2e5dd 100644
--- a/fs/ceph/mds_client.c
+++ b/fs/ceph/mds_client.c
@@ -2387,7 +2387,8 @@ static inline u64 __get_oldest_tid(struct ceph_mds_client *mdsc)
char *ceph_mdsc_build_path(struct dentry *dentry, int *plen, u64 *pbase,
int stop_on_nosnap)
{
- struct dentry *temp;
+ struct dentry *cur;
+ struct inode *inode;
char *path;
int pos;
unsigned seq;
@@ -2404,34 +2405,35 @@ retry:
path[pos] = '\0';
seq = read_seqbegin(&rename_lock);
- rcu_read_lock();
- temp = dentry;
+ cur = dget(dentry);
for (;;) {
- struct inode *inode;
+ struct dentry *temp;
- spin_lock(&temp->d_lock);
- inode = d_inode(temp);
+ spin_lock(&cur->d_lock);
+ inode = d_inode(cur);
if (inode && ceph_snap(inode) == CEPH_SNAPDIR) {
dout("build_path path+%d: %p SNAPDIR\n",
- pos, temp);
- } else if (stop_on_nosnap && inode && dentry != temp &&
+ pos, cur);
+ } else if (stop_on_nosnap && inode && dentry != cur &&
ceph_snap(inode) == CEPH_NOSNAP) {
- spin_unlock(&temp->d_lock);
+ spin_unlock(&cur->d_lock);
pos++; /* get rid of any prepended '/' */
break;
} else {
- pos -= temp->d_name.len;
+ pos -= cur->d_name.len;
if (pos < 0) {
- spin_unlock(&temp->d_lock);
+ spin_unlock(&cur->d_lock);
break;
}
- memcpy(path + pos, temp->d_name.name, temp->d_name.len);
+ memcpy(path + pos, cur->d_name.name, cur->d_name.len);
}
+ temp = cur;
spin_unlock(&temp->d_lock);
- temp = READ_ONCE(temp->d_parent);
+ cur = dget_parent(temp);
+ dput(temp);
/* Are we at the root? */
- if (IS_ROOT(temp))
+ if (IS_ROOT(cur))
break;
/* Are we out of buffer? */
@@ -2440,8 +2442,9 @@ retry:
path[pos] = '/';
}
- base = ceph_ino(d_inode(temp));
- rcu_read_unlock();
+ inode = d_inode(cur);
+ base = inode ? ceph_ino(inode) : 0;
+ dput(cur);
if (read_seqretry(&rename_lock, seq))
goto retry;