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linux-next/fs/ceph/export.c
Luis Henriques 878dabb641 ceph: don't return -ESTALE if there's still an open file 
Similarly to commit 03f219041f ("ceph: check i_nlink while converting
a file handle to dentry"), this fixes another corner case with
name_to_handle_at/open_by_handle_at.  The issue has been detected by
xfstest generic/467, when doing:

 - name_to_handle_at("/cephfs/myfile")
 - open("/cephfs/myfile")
 - unlink("/cephfs/myfile")
 - sync; sync;
 - drop caches
 - open_by_handle_at()

The call to open_by_handle_at should not fail because the file hasn't been
deleted yet (only unlinked) and we do have a valid handle to it.  -ESTALE
shall be returned only if i_nlink is 0 *and* i_count is 1.

This patch also makes sure we have LINK caps before checking i_nlink.

Signed-off-by: Luis Henriques <lhenriques@suse.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Acked-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
2020-06-01 13:22:53 +02:00

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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;
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);
}
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);
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)
return ERR_PTR(err);
/* -ESTALE if inode as been unlinked and no file is open */
if ((inode->i_nlink == 0) && (atomic_read(&inode->i_count) == 1)) {
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;
}
inode = ceph_find_inode(sb, vino);
if (inode)
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 */
err = -EOPNOTSUPP;
inode = NULL;
}
}
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 (!inode)
return ERR_PTR(-ESTALE);
/* 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);
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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