Message ID | 20210316203919.102346-1-jlayton@kernel.org (mailing list archive) |
---|---|
State | New, archived |
Headers | show |
Series | [v2] ceph: don't use d_add in ceph_handle_snapdir | expand |
On 2021/3/17 4:39, Jeff Layton wrote: > It's possible ceph_get_snapdir could end up finding a (disconnected) > inode that already exists in the cache. Change the prototype for > ceph_handle_snapdir to return a dentry pointer and have it use > d_splice_alias so we don't end up with an aliased dentry in the cache. > > URL: https://tracker.ceph.com/issues/49843 > Reported-by: Al Viro <viro@zeniv.linux.org.uk> > Signed-off-by: Jeff Layton <jlayton@kernel.org> > --- > fs/ceph/dir.c | 32 ++++++++++++++++++++------------ > fs/ceph/file.c | 7 +++++-- > fs/ceph/super.h | 2 +- > 3 files changed, 26 insertions(+), 15 deletions(-) > > v2: > zero out err var when ceph_handle_snapdir returns success > > diff --git a/fs/ceph/dir.c b/fs/ceph/dir.c > index 113f669d71dd..570662dec3fe 100644 > --- a/fs/ceph/dir.c > +++ b/fs/ceph/dir.c > @@ -667,8 +667,8 @@ static loff_t ceph_dir_llseek(struct file *file, loff_t offset, int whence) > /* > * Handle lookups for the hidden .snap directory. > */ > -int ceph_handle_snapdir(struct ceph_mds_request *req, > - struct dentry *dentry, int err) > +struct dentry *ceph_handle_snapdir(struct ceph_mds_request *req, > + struct dentry *dentry, int err) > { > struct ceph_fs_client *fsc = ceph_sb_to_client(dentry->d_sb); > struct inode *parent = d_inode(dentry->d_parent); /* we hold i_mutex */ > @@ -676,18 +676,19 @@ int ceph_handle_snapdir(struct ceph_mds_request *req, > /* .snap dir? */ > if (err == -ENOENT && > ceph_snap(parent) == CEPH_NOSNAP && > - strcmp(dentry->d_name.name, > - fsc->mount_options->snapdir_name) == 0) { > + strcmp(dentry->d_name.name, fsc->mount_options->snapdir_name) == 0) { > + struct dentry *res; > struct inode *inode = ceph_get_snapdir(parent); > + > if (IS_ERR(inode)) > - return PTR_ERR(inode); > - dout("ENOENT on snapdir %p '%pd', linking to snapdir %p\n", > - dentry, dentry, inode); > - BUG_ON(!d_unhashed(dentry)); > - d_add(dentry, inode); > - err = 0; > + return ERR_CAST(inode); > + res = d_splice_alias(inode, dentry); > + dout("ENOENT on snapdir %p '%pd', linking to snapdir %p. Spliced dentry %p\n", > + dentry, dentry, inode, res); > + if (res) > + dentry = res; > } > - return err; > + return dentry; > } > > /* > @@ -743,6 +744,7 @@ static struct dentry *ceph_lookup(struct inode *dir, struct dentry *dentry, > struct ceph_fs_client *fsc = ceph_sb_to_client(dir->i_sb); > struct ceph_mds_client *mdsc = ceph_sb_to_mdsc(dir->i_sb); > struct ceph_mds_request *req; > + struct dentry *res; > int op; > int mask; > int err; > @@ -793,7 +795,13 @@ static struct dentry *ceph_lookup(struct inode *dir, struct dentry *dentry, > req->r_parent = dir; > set_bit(CEPH_MDS_R_PARENT_LOCKED, &req->r_req_flags); > err = ceph_mdsc_do_request(mdsc, NULL, req); > - err = ceph_handle_snapdir(req, dentry, err); > + res = ceph_handle_snapdir(req, dentry, err); > + if (IS_ERR(res)) { > + err = PTR_ERR(res); > + } else { > + dentry = res; > + err = 0; > + } > dentry = ceph_finish_lookup(req, dentry, err); > ceph_mdsc_put_request(req); /* will dput(dentry) */ > dout("lookup result=%p\n", dentry); > diff --git a/fs/ceph/file.c b/fs/ceph/file.c > index 209535d5b8d3..a6ef1d143308 100644 > --- a/fs/ceph/file.c > +++ b/fs/ceph/file.c > @@ -739,9 +739,12 @@ int ceph_atomic_open(struct inode *dir, struct dentry *dentry, > err = ceph_mdsc_do_request(mdsc, > (flags & (O_CREAT|O_TRUNC)) ? dir : NULL, > req); > - err = ceph_handle_snapdir(req, dentry, err); > - if (err) > + dentry = ceph_handle_snapdir(req, dentry, err); > + if (IS_ERR(dentry)) { > + err = PTR_ERR(dentry); > goto out_req; > + } > + err = 0; > > if ((flags & O_CREAT) && !req->r_reply_info.head->is_dentry) > err = ceph_handle_notrace_create(dir, dentry); > diff --git a/fs/ceph/super.h b/fs/ceph/super.h > index 188565d806b2..07a3fb52ae30 100644 > --- a/fs/ceph/super.h > +++ b/fs/ceph/super.h > @@ -1193,7 +1193,7 @@ extern const struct dentry_operations ceph_dentry_ops; > > extern loff_t ceph_make_fpos(unsigned high, unsigned off, bool hash_order); > extern int ceph_handle_notrace_create(struct inode *dir, struct dentry *dentry); > -extern int ceph_handle_snapdir(struct ceph_mds_request *req, > +extern struct dentry *ceph_handle_snapdir(struct ceph_mds_request *req, > struct dentry *dentry, int err); > extern struct dentry *ceph_finish_lookup(struct ceph_mds_request *req, > struct dentry *dentry, int err); LGTM. Reviewed-by: Xiubo Li <xiubli@redhat.com>
diff --git a/fs/ceph/dir.c b/fs/ceph/dir.c index 113f669d71dd..570662dec3fe 100644 --- a/fs/ceph/dir.c +++ b/fs/ceph/dir.c @@ -667,8 +667,8 @@ static loff_t ceph_dir_llseek(struct file *file, loff_t offset, int whence) /* * Handle lookups for the hidden .snap directory. */ -int ceph_handle_snapdir(struct ceph_mds_request *req, - struct dentry *dentry, int err) +struct dentry *ceph_handle_snapdir(struct ceph_mds_request *req, + struct dentry *dentry, int err) { struct ceph_fs_client *fsc = ceph_sb_to_client(dentry->d_sb); struct inode *parent = d_inode(dentry->d_parent); /* we hold i_mutex */ @@ -676,18 +676,19 @@ int ceph_handle_snapdir(struct ceph_mds_request *req, /* .snap dir? */ if (err == -ENOENT && ceph_snap(parent) == CEPH_NOSNAP && - strcmp(dentry->d_name.name, - fsc->mount_options->snapdir_name) == 0) { + strcmp(dentry->d_name.name, fsc->mount_options->snapdir_name) == 0) { + struct dentry *res; struct inode *inode = ceph_get_snapdir(parent); + if (IS_ERR(inode)) - return PTR_ERR(inode); - dout("ENOENT on snapdir %p '%pd', linking to snapdir %p\n", - dentry, dentry, inode); - BUG_ON(!d_unhashed(dentry)); - d_add(dentry, inode); - err = 0; + return ERR_CAST(inode); + res = d_splice_alias(inode, dentry); + dout("ENOENT on snapdir %p '%pd', linking to snapdir %p. Spliced dentry %p\n", + dentry, dentry, inode, res); + if (res) + dentry = res; } - return err; + return dentry; } /* @@ -743,6 +744,7 @@ static struct dentry *ceph_lookup(struct inode *dir, struct dentry *dentry, struct ceph_fs_client *fsc = ceph_sb_to_client(dir->i_sb); struct ceph_mds_client *mdsc = ceph_sb_to_mdsc(dir->i_sb); struct ceph_mds_request *req; + struct dentry *res; int op; int mask; int err; @@ -793,7 +795,13 @@ static struct dentry *ceph_lookup(struct inode *dir, struct dentry *dentry, req->r_parent = dir; set_bit(CEPH_MDS_R_PARENT_LOCKED, &req->r_req_flags); err = ceph_mdsc_do_request(mdsc, NULL, req); - err = ceph_handle_snapdir(req, dentry, err); + res = ceph_handle_snapdir(req, dentry, err); + if (IS_ERR(res)) { + err = PTR_ERR(res); + } else { + dentry = res; + err = 0; + } dentry = ceph_finish_lookup(req, dentry, err); ceph_mdsc_put_request(req); /* will dput(dentry) */ dout("lookup result=%p\n", dentry); diff --git a/fs/ceph/file.c b/fs/ceph/file.c index 209535d5b8d3..a6ef1d143308 100644 --- a/fs/ceph/file.c +++ b/fs/ceph/file.c @@ -739,9 +739,12 @@ int ceph_atomic_open(struct inode *dir, struct dentry *dentry, err = ceph_mdsc_do_request(mdsc, (flags & (O_CREAT|O_TRUNC)) ? dir : NULL, req); - err = ceph_handle_snapdir(req, dentry, err); - if (err) + dentry = ceph_handle_snapdir(req, dentry, err); + if (IS_ERR(dentry)) { + err = PTR_ERR(dentry); goto out_req; + } + err = 0; if ((flags & O_CREAT) && !req->r_reply_info.head->is_dentry) err = ceph_handle_notrace_create(dir, dentry); diff --git a/fs/ceph/super.h b/fs/ceph/super.h index 188565d806b2..07a3fb52ae30 100644 --- a/fs/ceph/super.h +++ b/fs/ceph/super.h @@ -1193,7 +1193,7 @@ extern const struct dentry_operations ceph_dentry_ops; extern loff_t ceph_make_fpos(unsigned high, unsigned off, bool hash_order); extern int ceph_handle_notrace_create(struct inode *dir, struct dentry *dentry); -extern int ceph_handle_snapdir(struct ceph_mds_request *req, +extern struct dentry *ceph_handle_snapdir(struct ceph_mds_request *req, struct dentry *dentry, int err); extern struct dentry *ceph_finish_lookup(struct ceph_mds_request *req, struct dentry *dentry, int err);
It's possible ceph_get_snapdir could end up finding a (disconnected) inode that already exists in the cache. Change the prototype for ceph_handle_snapdir to return a dentry pointer and have it use d_splice_alias so we don't end up with an aliased dentry in the cache. URL: https://tracker.ceph.com/issues/49843 Reported-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Jeff Layton <jlayton@kernel.org> --- fs/ceph/dir.c | 32 ++++++++++++++++++++------------ fs/ceph/file.c | 7 +++++-- fs/ceph/super.h | 2 +- 3 files changed, 26 insertions(+), 15 deletions(-) v2: zero out err var when ceph_handle_snapdir returns success