linux-zen-server/fs/cifs/cached_dir.c

607 lines
14 KiB
C

// SPDX-License-Identifier: GPL-2.0
/*
* Functions to handle the cached directory entries
*
* Copyright (c) 2022, Ronnie Sahlberg <lsahlber@redhat.com>
*/
#include <linux/namei.h>
#include "cifsglob.h"
#include "cifsproto.h"
#include "cifs_debug.h"
#include "smb2proto.h"
#include "cached_dir.h"
static struct cached_fid *init_cached_dir(const char *path);
static void free_cached_dir(struct cached_fid *cfid);
static void smb2_close_cached_fid(struct kref *ref);
static struct cached_fid *find_or_create_cached_dir(struct cached_fids *cfids,
const char *path,
bool lookup_only)
{
struct cached_fid *cfid;
spin_lock(&cfids->cfid_list_lock);
list_for_each_entry(cfid, &cfids->entries, entry) {
if (!strcmp(cfid->path, path)) {
/*
* If it doesn't have a lease it is either not yet
* fully cached or it may be in the process of
* being deleted due to a lease break.
*/
if (!cfid->has_lease) {
spin_unlock(&cfids->cfid_list_lock);
return NULL;
}
kref_get(&cfid->refcount);
spin_unlock(&cfids->cfid_list_lock);
return cfid;
}
}
if (lookup_only) {
spin_unlock(&cfids->cfid_list_lock);
return NULL;
}
if (cfids->num_entries >= MAX_CACHED_FIDS) {
spin_unlock(&cfids->cfid_list_lock);
return NULL;
}
cfid = init_cached_dir(path);
if (cfid == NULL) {
spin_unlock(&cfids->cfid_list_lock);
return NULL;
}
cfid->cfids = cfids;
cfids->num_entries++;
list_add(&cfid->entry, &cfids->entries);
cfid->on_list = true;
kref_get(&cfid->refcount);
spin_unlock(&cfids->cfid_list_lock);
return cfid;
}
static struct dentry *
path_to_dentry(struct cifs_sb_info *cifs_sb, const char *path)
{
struct dentry *dentry;
const char *s, *p;
char sep;
sep = CIFS_DIR_SEP(cifs_sb);
dentry = dget(cifs_sb->root);
s = path;
do {
struct inode *dir = d_inode(dentry);
struct dentry *child;
if (!S_ISDIR(dir->i_mode)) {
dput(dentry);
dentry = ERR_PTR(-ENOTDIR);
break;
}
/* skip separators */
while (*s == sep)
s++;
if (!*s)
break;
p = s++;
/* next separator */
while (*s && *s != sep)
s++;
child = lookup_positive_unlocked(p, dentry, s - p);
dput(dentry);
dentry = child;
} while (!IS_ERR(dentry));
return dentry;
}
static const char *path_no_prefix(struct cifs_sb_info *cifs_sb,
const char *path)
{
size_t len = 0;
if (!*path)
return path;
if ((cifs_sb->mnt_cifs_flags & CIFS_MOUNT_USE_PREFIX_PATH) &&
cifs_sb->prepath) {
len = strlen(cifs_sb->prepath) + 1;
if (unlikely(len > strlen(path)))
return ERR_PTR(-EINVAL);
}
return path + len;
}
/*
* Open the and cache a directory handle.
* If error then *cfid is not initialized.
*/
int open_cached_dir(unsigned int xid, struct cifs_tcon *tcon,
const char *path,
struct cifs_sb_info *cifs_sb,
bool lookup_only, struct cached_fid **ret_cfid)
{
struct cifs_ses *ses;
struct TCP_Server_Info *server;
struct cifs_open_parms oparms;
struct smb2_create_rsp *o_rsp = NULL;
struct smb2_query_info_rsp *qi_rsp = NULL;
int resp_buftype[2];
struct smb_rqst rqst[2];
struct kvec rsp_iov[2];
struct kvec open_iov[SMB2_CREATE_IOV_SIZE];
struct kvec qi_iov[1];
int rc, flags = 0;
__le16 *utf16_path = NULL;
u8 oplock = SMB2_OPLOCK_LEVEL_II;
struct cifs_fid *pfid;
struct dentry *dentry = NULL;
struct cached_fid *cfid;
struct cached_fids *cfids;
const char *npath;
if (tcon == NULL || tcon->cfids == NULL || tcon->nohandlecache ||
is_smb1_server(tcon->ses->server))
return -EOPNOTSUPP;
ses = tcon->ses;
server = ses->server;
cfids = tcon->cfids;
if (!server->ops->new_lease_key)
return -EIO;
if (cifs_sb->root == NULL)
return -ENOENT;
utf16_path = cifs_convert_path_to_utf16(path, cifs_sb);
if (!utf16_path)
return -ENOMEM;
cfid = find_or_create_cached_dir(cfids, path, lookup_only);
if (cfid == NULL) {
kfree(utf16_path);
return -ENOENT;
}
/*
* At this point we either have a lease already and we can just
* return it. If not we are guaranteed to be the only thread accessing
* this cfid.
*/
if (cfid->has_lease) {
*ret_cfid = cfid;
kfree(utf16_path);
return 0;
}
/*
* Skip any prefix paths in @path as lookup_positive_unlocked() ends up
* calling ->lookup() which already adds those through
* build_path_from_dentry(). Also, do it earlier as we might reconnect
* below when trying to send compounded request and then potentially
* having a different prefix path (e.g. after DFS failover).
*/
npath = path_no_prefix(cifs_sb, path);
if (IS_ERR(npath)) {
rc = PTR_ERR(npath);
kfree(utf16_path);
return rc;
}
/*
* We do not hold the lock for the open because in case
* SMB2_open needs to reconnect.
* This is safe because no other thread will be able to get a ref
* to the cfid until we have finished opening the file and (possibly)
* acquired a lease.
*/
if (smb3_encryption_required(tcon))
flags |= CIFS_TRANSFORM_REQ;
pfid = &cfid->fid;
server->ops->new_lease_key(pfid);
memset(rqst, 0, sizeof(rqst));
resp_buftype[0] = resp_buftype[1] = CIFS_NO_BUFFER;
memset(rsp_iov, 0, sizeof(rsp_iov));
/* Open */
memset(&open_iov, 0, sizeof(open_iov));
rqst[0].rq_iov = open_iov;
rqst[0].rq_nvec = SMB2_CREATE_IOV_SIZE;
oparms = (struct cifs_open_parms) {
.tcon = tcon,
.path = path,
.create_options = cifs_create_options(cifs_sb, CREATE_NOT_FILE),
.desired_access = FILE_READ_ATTRIBUTES,
.disposition = FILE_OPEN,
.fid = pfid,
};
rc = SMB2_open_init(tcon, server,
&rqst[0], &oplock, &oparms, utf16_path);
if (rc)
goto oshr_free;
smb2_set_next_command(tcon, &rqst[0]);
memset(&qi_iov, 0, sizeof(qi_iov));
rqst[1].rq_iov = qi_iov;
rqst[1].rq_nvec = 1;
rc = SMB2_query_info_init(tcon, server,
&rqst[1], COMPOUND_FID,
COMPOUND_FID, FILE_ALL_INFORMATION,
SMB2_O_INFO_FILE, 0,
sizeof(struct smb2_file_all_info) +
PATH_MAX * 2, 0, NULL);
if (rc)
goto oshr_free;
smb2_set_related(&rqst[1]);
rc = compound_send_recv(xid, ses, server,
flags, 2, rqst,
resp_buftype, rsp_iov);
if (rc) {
if (rc == -EREMCHG) {
tcon->need_reconnect = true;
pr_warn_once("server share %s deleted\n",
tcon->tree_name);
}
goto oshr_free;
}
cfid->tcon = tcon;
cfid->is_open = true;
o_rsp = (struct smb2_create_rsp *)rsp_iov[0].iov_base;
oparms.fid->persistent_fid = o_rsp->PersistentFileId;
oparms.fid->volatile_fid = o_rsp->VolatileFileId;
#ifdef CONFIG_CIFS_DEBUG2
oparms.fid->mid = le64_to_cpu(o_rsp->hdr.MessageId);
#endif /* CIFS_DEBUG2 */
if (o_rsp->OplockLevel != SMB2_OPLOCK_LEVEL_LEASE)
goto oshr_free;
smb2_parse_contexts(server, o_rsp,
&oparms.fid->epoch,
oparms.fid->lease_key, &oplock,
NULL, NULL);
if (!(oplock & SMB2_LEASE_READ_CACHING_HE))
goto oshr_free;
qi_rsp = (struct smb2_query_info_rsp *)rsp_iov[1].iov_base;
if (le32_to_cpu(qi_rsp->OutputBufferLength) < sizeof(struct smb2_file_all_info))
goto oshr_free;
if (!smb2_validate_and_copy_iov(
le16_to_cpu(qi_rsp->OutputBufferOffset),
sizeof(struct smb2_file_all_info),
&rsp_iov[1], sizeof(struct smb2_file_all_info),
(char *)&cfid->file_all_info))
cfid->file_all_info_is_valid = true;
if (!npath[0])
dentry = dget(cifs_sb->root);
else {
dentry = path_to_dentry(cifs_sb, npath);
if (IS_ERR(dentry)) {
rc = -ENOENT;
goto oshr_free;
}
}
cfid->dentry = dentry;
cfid->time = jiffies;
cfid->has_lease = true;
oshr_free:
kfree(utf16_path);
SMB2_open_free(&rqst[0]);
SMB2_query_info_free(&rqst[1]);
free_rsp_buf(resp_buftype[0], rsp_iov[0].iov_base);
free_rsp_buf(resp_buftype[1], rsp_iov[1].iov_base);
spin_lock(&cfids->cfid_list_lock);
if (rc && !cfid->has_lease) {
if (cfid->on_list) {
list_del(&cfid->entry);
cfid->on_list = false;
cfids->num_entries--;
}
rc = -ENOENT;
}
spin_unlock(&cfids->cfid_list_lock);
if (!rc && !cfid->has_lease) {
/*
* We are guaranteed to have two references at this point.
* One for the caller and one for a potential lease.
* Release the Lease-ref so that the directory will be closed
* when the caller closes the cached handle.
*/
kref_put(&cfid->refcount, smb2_close_cached_fid);
}
if (rc) {
if (cfid->is_open)
SMB2_close(0, cfid->tcon, cfid->fid.persistent_fid,
cfid->fid.volatile_fid);
free_cached_dir(cfid);
cfid = NULL;
}
if (rc == 0) {
*ret_cfid = cfid;
atomic_inc(&tcon->num_remote_opens);
}
return rc;
}
int open_cached_dir_by_dentry(struct cifs_tcon *tcon,
struct dentry *dentry,
struct cached_fid **ret_cfid)
{
struct cached_fid *cfid;
struct cached_fids *cfids = tcon->cfids;
if (cfids == NULL)
return -ENOENT;
spin_lock(&cfids->cfid_list_lock);
list_for_each_entry(cfid, &cfids->entries, entry) {
if (dentry && cfid->dentry == dentry) {
cifs_dbg(FYI, "found a cached root file handle by dentry\n");
kref_get(&cfid->refcount);
*ret_cfid = cfid;
spin_unlock(&cfids->cfid_list_lock);
return 0;
}
}
spin_unlock(&cfids->cfid_list_lock);
return -ENOENT;
}
static void
smb2_close_cached_fid(struct kref *ref)
{
struct cached_fid *cfid = container_of(ref, struct cached_fid,
refcount);
spin_lock(&cfid->cfids->cfid_list_lock);
if (cfid->on_list) {
list_del(&cfid->entry);
cfid->on_list = false;
cfid->cfids->num_entries--;
}
spin_unlock(&cfid->cfids->cfid_list_lock);
dput(cfid->dentry);
cfid->dentry = NULL;
if (cfid->is_open) {
SMB2_close(0, cfid->tcon, cfid->fid.persistent_fid,
cfid->fid.volatile_fid);
atomic_dec(&cfid->tcon->num_remote_opens);
}
free_cached_dir(cfid);
}
void drop_cached_dir_by_name(const unsigned int xid, struct cifs_tcon *tcon,
const char *name, struct cifs_sb_info *cifs_sb)
{
struct cached_fid *cfid = NULL;
int rc;
rc = open_cached_dir(xid, tcon, name, cifs_sb, true, &cfid);
if (rc) {
cifs_dbg(FYI, "no cached dir found for rmdir(%s)\n", name);
return;
}
spin_lock(&cfid->cfids->cfid_list_lock);
if (cfid->has_lease) {
cfid->has_lease = false;
kref_put(&cfid->refcount, smb2_close_cached_fid);
}
spin_unlock(&cfid->cfids->cfid_list_lock);
close_cached_dir(cfid);
}
void close_cached_dir(struct cached_fid *cfid)
{
kref_put(&cfid->refcount, smb2_close_cached_fid);
}
/*
* Called from cifs_kill_sb when we unmount a share
*/
void close_all_cached_dirs(struct cifs_sb_info *cifs_sb)
{
struct rb_root *root = &cifs_sb->tlink_tree;
struct rb_node *node;
struct cached_fid *cfid;
struct cifs_tcon *tcon;
struct tcon_link *tlink;
struct cached_fids *cfids;
for (node = rb_first(root); node; node = rb_next(node)) {
tlink = rb_entry(node, struct tcon_link, tl_rbnode);
tcon = tlink_tcon(tlink);
if (IS_ERR(tcon))
continue;
cfids = tcon->cfids;
if (cfids == NULL)
continue;
list_for_each_entry(cfid, &cfids->entries, entry) {
dput(cfid->dentry);
cfid->dentry = NULL;
}
}
}
/*
* Invalidate all cached dirs when a TCON has been reset
* due to a session loss.
*/
void invalidate_all_cached_dirs(struct cifs_tcon *tcon)
{
struct cached_fids *cfids = tcon->cfids;
struct cached_fid *cfid, *q;
LIST_HEAD(entry);
spin_lock(&cfids->cfid_list_lock);
list_for_each_entry_safe(cfid, q, &cfids->entries, entry) {
list_move(&cfid->entry, &entry);
cfids->num_entries--;
cfid->is_open = false;
cfid->on_list = false;
/* To prevent race with smb2_cached_lease_break() */
kref_get(&cfid->refcount);
}
spin_unlock(&cfids->cfid_list_lock);
list_for_each_entry_safe(cfid, q, &entry, entry) {
list_del(&cfid->entry);
cancel_work_sync(&cfid->lease_break);
if (cfid->has_lease) {
/*
* We lease was never cancelled from the server so we
* need to drop the reference.
*/
spin_lock(&cfids->cfid_list_lock);
cfid->has_lease = false;
spin_unlock(&cfids->cfid_list_lock);
kref_put(&cfid->refcount, smb2_close_cached_fid);
}
/* Drop the extra reference opened above*/
kref_put(&cfid->refcount, smb2_close_cached_fid);
}
}
static void
smb2_cached_lease_break(struct work_struct *work)
{
struct cached_fid *cfid = container_of(work,
struct cached_fid, lease_break);
spin_lock(&cfid->cfids->cfid_list_lock);
cfid->has_lease = false;
spin_unlock(&cfid->cfids->cfid_list_lock);
kref_put(&cfid->refcount, smb2_close_cached_fid);
}
int cached_dir_lease_break(struct cifs_tcon *tcon, __u8 lease_key[16])
{
struct cached_fids *cfids = tcon->cfids;
struct cached_fid *cfid;
if (cfids == NULL)
return false;
spin_lock(&cfids->cfid_list_lock);
list_for_each_entry(cfid, &cfids->entries, entry) {
if (cfid->has_lease &&
!memcmp(lease_key,
cfid->fid.lease_key,
SMB2_LEASE_KEY_SIZE)) {
cfid->time = 0;
/*
* We found a lease remove it from the list
* so no threads can access it.
*/
list_del(&cfid->entry);
cfid->on_list = false;
cfids->num_entries--;
queue_work(cifsiod_wq,
&cfid->lease_break);
spin_unlock(&cfids->cfid_list_lock);
return true;
}
}
spin_unlock(&cfids->cfid_list_lock);
return false;
}
static struct cached_fid *init_cached_dir(const char *path)
{
struct cached_fid *cfid;
cfid = kzalloc(sizeof(*cfid), GFP_ATOMIC);
if (!cfid)
return NULL;
cfid->path = kstrdup(path, GFP_ATOMIC);
if (!cfid->path) {
kfree(cfid);
return NULL;
}
INIT_WORK(&cfid->lease_break, smb2_cached_lease_break);
INIT_LIST_HEAD(&cfid->entry);
INIT_LIST_HEAD(&cfid->dirents.entries);
mutex_init(&cfid->dirents.de_mutex);
spin_lock_init(&cfid->fid_lock);
kref_init(&cfid->refcount);
return cfid;
}
static void free_cached_dir(struct cached_fid *cfid)
{
struct cached_dirent *dirent, *q;
dput(cfid->dentry);
cfid->dentry = NULL;
/*
* Delete all cached dirent names
*/
list_for_each_entry_safe(dirent, q, &cfid->dirents.entries, entry) {
list_del(&dirent->entry);
kfree(dirent->name);
kfree(dirent);
}
kfree(cfid->path);
cfid->path = NULL;
kfree(cfid);
}
struct cached_fids *init_cached_dirs(void)
{
struct cached_fids *cfids;
cfids = kzalloc(sizeof(*cfids), GFP_KERNEL);
if (!cfids)
return NULL;
spin_lock_init(&cfids->cfid_list_lock);
INIT_LIST_HEAD(&cfids->entries);
return cfids;
}
/*
* Called from tconInfoFree when we are tearing down the tcon.
* There are no active users or open files/directories at this point.
*/
void free_cached_dirs(struct cached_fids *cfids)
{
struct cached_fid *cfid, *q;
LIST_HEAD(entry);
spin_lock(&cfids->cfid_list_lock);
list_for_each_entry_safe(cfid, q, &cfids->entries, entry) {
cfid->on_list = false;
cfid->is_open = false;
list_move(&cfid->entry, &entry);
}
spin_unlock(&cfids->cfid_list_lock);
list_for_each_entry_safe(cfid, q, &entry, entry) {
list_del(&cfid->entry);
free_cached_dir(cfid);
}
kfree(cfids);
}