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linux/fs/ceph/export.c
Xiubo Li bd04b9192e ceph: fail the open_by_handle_at() if the dentry is being unlinked 
When unlinking a file the kclient will send a unlink request to MDS
by holding the dentry reference, and then the MDS will return 2 replies,
which are unsafe reply and a deferred safe reply.

After the unsafe reply received the kernel will return and succeed
the unlink request to user space apps.

Only when the safe reply received the dentry's reference will be
released. Or the dentry will only be unhashed from dcache. But when
the open_by_handle_at() begins to open the unlinked files it will
succeed.

The inode->i_count couldn't be used to check whether the inode is
opened or not.

Link: https://tracker.ceph.com/issues/56524
Signed-off-by: Xiubo Li <xiubli@redhat.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: Luís Henriques <lhenriques@suse.de>
Tested-by: Luís Henriques <lhenriques@suse.de>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
2022-10-04 19:18:08 +02:00

585 lines
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// SPDX-License-Identifier: GPL-2.0
#include <linux/ceph/ceph_debug.h>
#include <linux/exportfs.h>
#include <linux/slab.h>
#include <asm/unaligned.h>
#include "super.h"
#include "mds_client.h"
/*
* Basic fh
*/
struct ceph_nfs_fh {
u64 ino;
} __attribute__ ((packed));
/*
* Larger fh that includes parent ino.
*/
struct ceph_nfs_confh {
u64 ino, parent_ino;
} __attribute__ ((packed));
/*
* fh for snapped inode
*/
struct ceph_nfs_snapfh {
u64 ino;
u64 snapid;
u64 parent_ino;
u32 hash;
} __attribute__ ((packed));
static int ceph_encode_snapfh(struct inode *inode, u32 *rawfh, int *max_len,
struct inode *parent_inode)
{
static const int snap_handle_length =
sizeof(struct ceph_nfs_snapfh) >> 2;
struct ceph_nfs_snapfh *sfh = (void *)rawfh;
u64 snapid = ceph_snap(inode);
int ret;
bool no_parent = true;
if (*max_len < snap_handle_length) {
*max_len = snap_handle_length;
ret = FILEID_INVALID;
goto out;
}
ret = -EINVAL;
if (snapid != CEPH_SNAPDIR) {
struct inode *dir;
struct dentry *dentry = d_find_alias(inode);
if (!dentry)
goto out;
rcu_read_lock();
dir = d_inode_rcu(dentry->d_parent);
if (ceph_snap(dir) != CEPH_SNAPDIR) {
sfh->parent_ino = ceph_ino(dir);
sfh->hash = ceph_dentry_hash(dir, dentry);
no_parent = false;
}
rcu_read_unlock();
dput(dentry);
}
if (no_parent) {
if (!S_ISDIR(inode->i_mode))
goto out;
sfh->parent_ino = sfh->ino;
sfh->hash = 0;
}
sfh->ino = ceph_ino(inode);
sfh->snapid = snapid;
*max_len = snap_handle_length;
ret = FILEID_BTRFS_WITH_PARENT;
out:
dout("encode_snapfh %llx.%llx ret=%d\n", ceph_vinop(inode), ret);
return ret;
}
static int ceph_encode_fh(struct inode *inode, u32 *rawfh, int *max_len,
struct inode *parent_inode)
{
static const int handle_length =
sizeof(struct ceph_nfs_fh) >> 2;
static const int connected_handle_length =
sizeof(struct ceph_nfs_confh) >> 2;
int type;
if (ceph_snap(inode) != CEPH_NOSNAP)
return ceph_encode_snapfh(inode, rawfh, max_len, parent_inode);
if (parent_inode && (*max_len < connected_handle_length)) {
*max_len = connected_handle_length;
return FILEID_INVALID;
} else if (*max_len < handle_length) {
*max_len = handle_length;
return FILEID_INVALID;
}
if (parent_inode) {
struct ceph_nfs_confh *cfh = (void *)rawfh;
dout("encode_fh %llx with parent %llx\n",
ceph_ino(inode), ceph_ino(parent_inode));
cfh->ino = ceph_ino(inode);
cfh->parent_ino = ceph_ino(parent_inode);
*max_len = connected_handle_length;
type = FILEID_INO32_GEN_PARENT;
} else {
struct ceph_nfs_fh *fh = (void *)rawfh;
dout("encode_fh %llx\n", ceph_ino(inode));
fh->ino = ceph_ino(inode);
*max_len = handle_length;
type = FILEID_INO32_GEN;
}
return type;
}
static struct inode *__lookup_inode(struct super_block *sb, u64 ino)
{
struct ceph_mds_client *mdsc = ceph_sb_to_client(sb)->mdsc;
struct inode *inode;
struct ceph_vino vino;
int err;
vino.ino = ino;
vino.snap = CEPH_NOSNAP;
if (ceph_vino_is_reserved(vino))
return ERR_PTR(-ESTALE);
inode = ceph_find_inode(sb, vino);
if (!inode) {
struct ceph_mds_request *req;
int mask;
req = ceph_mdsc_create_request(mdsc, CEPH_MDS_OP_LOOKUPINO,
USE_ANY_MDS);
if (IS_ERR(req))
return ERR_CAST(req);
mask = CEPH_STAT_CAP_INODE;
if (ceph_security_xattr_wanted(d_inode(sb->s_root)))
mask |= CEPH_CAP_XATTR_SHARED;
req->r_args.lookupino.mask = cpu_to_le32(mask);
req->r_ino1 = vino;
req->r_num_caps = 1;
err = ceph_mdsc_do_request(mdsc, NULL, req);
inode = req->r_target_inode;
if (inode)
ihold(inode);
ceph_mdsc_put_request(req);
if (!inode)
return err < 0 ? ERR_PTR(err) : ERR_PTR(-ESTALE);
} else {
if (ceph_inode_is_shutdown(inode)) {
iput(inode);
return ERR_PTR(-ESTALE);
}
}
return inode;
}
struct inode *ceph_lookup_inode(struct super_block *sb, u64 ino)
{
struct inode *inode = __lookup_inode(sb, ino);
if (IS_ERR(inode))
return inode;
if (inode->i_nlink == 0) {
iput(inode);
return ERR_PTR(-ESTALE);
}
return inode;
}
static struct dentry *__fh_to_dentry(struct super_block *sb, u64 ino)
{
struct inode *inode = __lookup_inode(sb, ino);
struct ceph_inode_info *ci = ceph_inode(inode);
int err;
if (IS_ERR(inode))
return ERR_CAST(inode);
/* We need LINK caps to reliably check i_nlink */
err = ceph_do_getattr(inode, CEPH_CAP_LINK_SHARED, false);
if (err) {
iput(inode);
return ERR_PTR(err);
}
/* -ESTALE if inode as been unlinked and no file is open */
if ((inode->i_nlink == 0) && !__ceph_is_file_opened(ci)) {
iput(inode);
return ERR_PTR(-ESTALE);
}
return d_obtain_alias(inode);
}
static struct dentry *__snapfh_to_dentry(struct super_block *sb,
struct ceph_nfs_snapfh *sfh,
bool want_parent)
{
struct ceph_mds_client *mdsc = ceph_sb_to_client(sb)->mdsc;
struct ceph_mds_request *req;
struct inode *inode;
struct ceph_vino vino;
int mask;
int err;
bool unlinked = false;
if (want_parent) {
vino.ino = sfh->parent_ino;
if (sfh->snapid == CEPH_SNAPDIR)
vino.snap = CEPH_NOSNAP;
else if (sfh->ino == sfh->parent_ino)
vino.snap = CEPH_SNAPDIR;
else
vino.snap = sfh->snapid;
} else {
vino.ino = sfh->ino;
vino.snap = sfh->snapid;
}
if (ceph_vino_is_reserved(vino))
return ERR_PTR(-ESTALE);
inode = ceph_find_inode(sb, vino);
if (inode) {
if (ceph_inode_is_shutdown(inode)) {
iput(inode);
return ERR_PTR(-ESTALE);
}
return d_obtain_alias(inode);
}
req = ceph_mdsc_create_request(mdsc, CEPH_MDS_OP_LOOKUPINO,
USE_ANY_MDS);
if (IS_ERR(req))
return ERR_CAST(req);
mask = CEPH_STAT_CAP_INODE;
if (ceph_security_xattr_wanted(d_inode(sb->s_root)))
mask |= CEPH_CAP_XATTR_SHARED;
req->r_args.lookupino.mask = cpu_to_le32(mask);
if (vino.snap < CEPH_NOSNAP) {
req->r_args.lookupino.snapid = cpu_to_le64(vino.snap);
if (!want_parent && sfh->ino != sfh->parent_ino) {
req->r_args.lookupino.parent =
cpu_to_le64(sfh->parent_ino);
req->r_args.lookupino.hash =
cpu_to_le32(sfh->hash);
}
}
req->r_ino1 = vino;
req->r_num_caps = 1;
err = ceph_mdsc_do_request(mdsc, NULL, req);
inode = req->r_target_inode;
if (inode) {
if (vino.snap == CEPH_SNAPDIR) {
if (inode->i_nlink == 0)
unlinked = true;
inode = ceph_get_snapdir(inode);
} else if (ceph_snap(inode) == vino.snap) {
ihold(inode);
} else {
/* mds does not support lookup snapped inode */
inode = ERR_PTR(-EOPNOTSUPP);
}
} else {
inode = ERR_PTR(-ESTALE);
}
ceph_mdsc_put_request(req);
if (want_parent) {
dout("snapfh_to_parent %llx.%llx\n err=%d\n",
vino.ino, vino.snap, err);
} else {
dout("snapfh_to_dentry %llx.%llx parent %llx hash %x err=%d",
vino.ino, vino.snap, sfh->parent_ino, sfh->hash, err);
}
if (IS_ERR(inode))
return ERR_CAST(inode);
/* see comments in ceph_get_parent() */
return unlinked ? d_obtain_root(inode) : d_obtain_alias(inode);
}
/*
* convert regular fh to dentry
*/
static struct dentry *ceph_fh_to_dentry(struct super_block *sb,
struct fid *fid,
int fh_len, int fh_type)
{
struct ceph_nfs_fh *fh = (void *)fid->raw;
if (fh_type == FILEID_BTRFS_WITH_PARENT) {
struct ceph_nfs_snapfh *sfh = (void *)fid->raw;
return __snapfh_to_dentry(sb, sfh, false);
}
if (fh_type != FILEID_INO32_GEN &&
fh_type != FILEID_INO32_GEN_PARENT)
return NULL;
if (fh_len < sizeof(*fh) / 4)
return NULL;
dout("fh_to_dentry %llx\n", fh->ino);
return __fh_to_dentry(sb, fh->ino);
}
static struct dentry *__get_parent(struct super_block *sb,
struct dentry *child, u64 ino)
{
struct ceph_mds_client *mdsc = ceph_sb_to_client(sb)->mdsc;
struct ceph_mds_request *req;
struct inode *inode;
int mask;
int err;
req = ceph_mdsc_create_request(mdsc, CEPH_MDS_OP_LOOKUPPARENT,
USE_ANY_MDS);
if (IS_ERR(req))
return ERR_CAST(req);
if (child) {
req->r_inode = d_inode(child);
ihold(d_inode(child));
} else {
req->r_ino1 = (struct ceph_vino) {
.ino = ino,
.snap = CEPH_NOSNAP,
};
}
mask = CEPH_STAT_CAP_INODE;
if (ceph_security_xattr_wanted(d_inode(sb->s_root)))
mask |= CEPH_CAP_XATTR_SHARED;
req->r_args.getattr.mask = cpu_to_le32(mask);
req->r_num_caps = 1;
err = ceph_mdsc_do_request(mdsc, NULL, req);
if (err) {
ceph_mdsc_put_request(req);
return ERR_PTR(err);
}
inode = req->r_target_inode;
if (inode)
ihold(inode);
ceph_mdsc_put_request(req);
if (!inode)
return ERR_PTR(-ENOENT);
return d_obtain_alias(inode);
}
static struct dentry *ceph_get_parent(struct dentry *child)
{
struct inode *inode = d_inode(child);
struct dentry *dn;
if (ceph_snap(inode) != CEPH_NOSNAP) {
struct inode* dir;
bool unlinked = false;
/* do not support non-directory */
if (!d_is_dir(child)) {
dn = ERR_PTR(-EINVAL);
goto out;
}
dir = __lookup_inode(inode->i_sb, ceph_ino(inode));
if (IS_ERR(dir)) {
dn = ERR_CAST(dir);
goto out;
}
/* There can be multiple paths to access snapped inode.
* For simplicity, treat snapdir of head inode as parent */
if (ceph_snap(inode) != CEPH_SNAPDIR) {
struct inode *snapdir = ceph_get_snapdir(dir);
if (dir->i_nlink == 0)
unlinked = true;
iput(dir);
if (IS_ERR(snapdir)) {
dn = ERR_CAST(snapdir);
goto out;
}
dir = snapdir;
}
/* If directory has already been deleted, futher get_parent
* will fail. Do not mark snapdir dentry as disconnected,
* this prevent exportfs from doing futher get_parent. */
if (unlinked)
dn = d_obtain_root(dir);
else
dn = d_obtain_alias(dir);
} else {
dn = __get_parent(child->d_sb, child, 0);
}
out:
dout("get_parent %p ino %llx.%llx err=%ld\n",
child, ceph_vinop(inode), (long)PTR_ERR_OR_ZERO(dn));
return dn;
}
/*
* convert regular fh to parent
*/
static struct dentry *ceph_fh_to_parent(struct super_block *sb,
struct fid *fid,
int fh_len, int fh_type)
{
struct ceph_nfs_confh *cfh = (void *)fid->raw;
struct dentry *dentry;
if (fh_type == FILEID_BTRFS_WITH_PARENT) {
struct ceph_nfs_snapfh *sfh = (void *)fid->raw;
return __snapfh_to_dentry(sb, sfh, true);
}
if (fh_type != FILEID_INO32_GEN_PARENT)
return NULL;
if (fh_len < sizeof(*cfh) / 4)
return NULL;
dout("fh_to_parent %llx\n", cfh->parent_ino);
dentry = __get_parent(sb, NULL, cfh->ino);
if (unlikely(dentry == ERR_PTR(-ENOENT)))
dentry = __fh_to_dentry(sb, cfh->parent_ino);
return dentry;
}
static int __get_snap_name(struct dentry *parent, char *name,
struct dentry *child)
{
struct inode *inode = d_inode(child);
struct inode *dir = d_inode(parent);
struct ceph_fs_client *fsc = ceph_inode_to_client(inode);
struct ceph_mds_request *req = NULL;
char *last_name = NULL;
unsigned next_offset = 2;
int err = -EINVAL;
if (ceph_ino(inode) != ceph_ino(dir))
goto out;
if (ceph_snap(inode) == CEPH_SNAPDIR) {
if (ceph_snap(dir) == CEPH_NOSNAP) {
strcpy(name, fsc->mount_options->snapdir_name);
err = 0;
}
goto out;
}
if (ceph_snap(dir) != CEPH_SNAPDIR)
goto out;
while (1) {
struct ceph_mds_reply_info_parsed *rinfo;
struct ceph_mds_reply_dir_entry *rde;
int i;
req = ceph_mdsc_create_request(fsc->mdsc, CEPH_MDS_OP_LSSNAP,
USE_AUTH_MDS);
if (IS_ERR(req)) {
err = PTR_ERR(req);
req = NULL;
goto out;
}
err = ceph_alloc_readdir_reply_buffer(req, inode);
if (err)
goto out;
req->r_direct_mode = USE_AUTH_MDS;
req->r_readdir_offset = next_offset;
req->r_args.readdir.flags =
cpu_to_le16(CEPH_READDIR_REPLY_BITFLAGS);
if (last_name) {
req->r_path2 = last_name;
last_name = NULL;
}
req->r_inode = dir;
ihold(dir);
req->r_dentry = dget(parent);
inode_lock(dir);
err = ceph_mdsc_do_request(fsc->mdsc, NULL, req);
inode_unlock(dir);
if (err < 0)
goto out;
rinfo = &req->r_reply_info;
for (i = 0; i < rinfo->dir_nr; i++) {
rde = rinfo->dir_entries + i;
BUG_ON(!rde->inode.in);
if (ceph_snap(inode) ==
le64_to_cpu(rde->inode.in->snapid)) {
memcpy(name, rde->name, rde->name_len);
name[rde->name_len] = '\0';
err = 0;
goto out;
}
}
if (rinfo->dir_end)
break;
BUG_ON(rinfo->dir_nr <= 0);
rde = rinfo->dir_entries + (rinfo->dir_nr - 1);
next_offset += rinfo->dir_nr;
last_name = kstrndup(rde->name, rde->name_len, GFP_KERNEL);
if (!last_name) {
err = -ENOMEM;
goto out;
}
ceph_mdsc_put_request(req);
req = NULL;
}
err = -ENOENT;
out:
if (req)
ceph_mdsc_put_request(req);
kfree(last_name);
dout("get_snap_name %p ino %llx.%llx err=%d\n",
child, ceph_vinop(inode), err);
return err;
}
static int ceph_get_name(struct dentry *parent, char *name,
struct dentry *child)
{
struct ceph_mds_client *mdsc;
struct ceph_mds_request *req;
struct inode *inode = d_inode(child);
int err;
if (ceph_snap(inode) != CEPH_NOSNAP)
return __get_snap_name(parent, name, child);
mdsc = ceph_inode_to_client(inode)->mdsc;
req = ceph_mdsc_create_request(mdsc, CEPH_MDS_OP_LOOKUPNAME,
USE_ANY_MDS);
if (IS_ERR(req))
return PTR_ERR(req);
inode_lock(d_inode(parent));
req->r_inode = inode;
ihold(inode);
req->r_ino2 = ceph_vino(d_inode(parent));
req->r_parent = d_inode(parent);
ihold(req->r_parent);
set_bit(CEPH_MDS_R_PARENT_LOCKED, &req->r_req_flags);
req->r_num_caps = 2;
err = ceph_mdsc_do_request(mdsc, NULL, req);
inode_unlock(d_inode(parent));
if (!err) {
struct ceph_mds_reply_info_parsed *rinfo = &req->r_reply_info;
memcpy(name, rinfo->dname, rinfo->dname_len);
name[rinfo->dname_len] = 0;
dout("get_name %p ino %llx.%llx name %s\n",
child, ceph_vinop(inode), name);
} else {
dout("get_name %p ino %llx.%llx err %d\n",
child, ceph_vinop(inode), err);
}
ceph_mdsc_put_request(req);
return err;
}
const struct export_operations ceph_export_ops = {
.encode_fh = ceph_encode_fh,
.fh_to_dentry = ceph_fh_to_dentry,
.fh_to_parent = ceph_fh_to_parent,
.get_parent = ceph_get_parent,
.get_name = ceph_get_name,
};
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