fs/cifs/cached_dir.c

0001 // SPDX-License-Identifier: GPL-2.0
0002 /*
0003  *  Functions to handle the cached directory entries
0004  *
0005  *  Copyright (c) 2022, Ronnie Sahlberg <lsahlber@redhat.com>
0006  */
0007
0008 #include "cifsglob.h"
0009 #include "cifsproto.h"
0010 #include "cifs_debug.h"
0011 #include "smb2proto.h"
0012 #include "cached_dir.h"
0013
0014 /*
0015  * Open the and cache a directory handle.
0016  * If error then *cfid is not initialized.
0017  */
0018 int open_cached_dir(unsigned int xid, struct cifs_tcon *tcon,
0019             const char *path,
0020             struct cifs_sb_info *cifs_sb,
0021             bool lookup_only, struct cached_fid **ret_cfid)
0022 {
0023     struct cifs_ses *ses;
0024     struct TCP_Server_Info *server;
0025     struct cifs_open_parms oparms;
0026     struct smb2_create_rsp *o_rsp = NULL;
0027     struct smb2_query_info_rsp *qi_rsp = NULL;
0028     int resp_buftype[2];
0029     struct smb_rqst rqst[2];
0030     struct kvec rsp_iov[2];
0031     struct kvec open_iov[SMB2_CREATE_IOV_SIZE];
0032     struct kvec qi_iov[1];
0033     int rc, flags = 0;
0034     __le16 utf16_path = 0; /* Null - since an open of top of share */
0035     u8 oplock = SMB2_OPLOCK_LEVEL_II;
0036     struct cifs_fid *pfid;
0037     struct dentry *dentry;
0038     struct cached_fid *cfid;
0039
0040     if (tcon == NULL || tcon->nohandlecache ||
0041         is_smb1_server(tcon->ses->server))
0042         return -EOPNOTSUPP;
0043
0044     ses = tcon->ses;
0045     server = ses->server;
0046
0047     if (cifs_sb->root == NULL)
0048         return -ENOENT;
0049
0050     if (strlen(path))
0051         return -ENOENT;
0052
0053     dentry = cifs_sb->root;
0054
0055     cfid = tcon->cfid;
0056     mutex_lock(&cfid->fid_mutex);
0057     if (cfid->is_valid) {
0058         cifs_dbg(FYI, "found a cached root file handle\n");
0059         *ret_cfid = cfid;
0060         kref_get(&cfid->refcount);
0061         mutex_unlock(&cfid->fid_mutex);
0062         return 0;
0063     }
0064
0065     /*
0066      * We do not hold the lock for the open because in case
0067      * SMB2_open needs to reconnect, it will end up calling
0068      * cifs_mark_open_files_invalid() which takes the lock again
0069      * thus causing a deadlock
0070      */
0071     mutex_unlock(&cfid->fid_mutex);
0072
0073     if (lookup_only)
0074         return -ENOENT;
0075
0076     if (smb3_encryption_required(tcon))
0077         flags |= CIFS_TRANSFORM_REQ;
0078
0079     if (!server->ops->new_lease_key)
0080         return -EIO;
0081
0082     pfid = &cfid->fid;
0083     server->ops->new_lease_key(pfid);
0084
0085     memset(rqst, 0, sizeof(rqst));
0086     resp_buftype[0] = resp_buftype[1] = CIFS_NO_BUFFER;
0087     memset(rsp_iov, 0, sizeof(rsp_iov));
0088
0089     /* Open */
0090     memset(&open_iov, 0, sizeof(open_iov));
0091     rqst[0].rq_iov = open_iov;
0092     rqst[0].rq_nvec = SMB2_CREATE_IOV_SIZE;
0093
0094     oparms.tcon = tcon;
0095     oparms.create_options = cifs_create_options(cifs_sb, CREATE_NOT_FILE);
0096     oparms.desired_access = FILE_READ_ATTRIBUTES;
0097     oparms.disposition = FILE_OPEN;
0098     oparms.fid = pfid;
0099     oparms.reconnect = false;
0100
0101     rc = SMB2_open_init(tcon, server,
0102                 &rqst[0], &oplock, &oparms, &utf16_path);
0103     if (rc)
0104         goto oshr_free;
0105     smb2_set_next_command(tcon, &rqst[0]);
0106
0107     memset(&qi_iov, 0, sizeof(qi_iov));
0108     rqst[1].rq_iov = qi_iov;
0109     rqst[1].rq_nvec = 1;
0110
0111     rc = SMB2_query_info_init(tcon, server,
0112                   &rqst[1], COMPOUND_FID,
0113                   COMPOUND_FID, FILE_ALL_INFORMATION,
0114                   SMB2_O_INFO_FILE, 0,
0115                   sizeof(struct smb2_file_all_info) +
0116                   PATH_MAX * 2, 0, NULL);
0117     if (rc)
0118         goto oshr_free;
0119
0120     smb2_set_related(&rqst[1]);
0121
0122     rc = compound_send_recv(xid, ses, server,
0123                 flags, 2, rqst,
0124                 resp_buftype, rsp_iov);
0125     mutex_lock(&cfid->fid_mutex);
0126
0127     /*
0128      * Now we need to check again as the cached root might have
0129      * been successfully re-opened from a concurrent process
0130      */
0131
0132     if (cfid->is_valid) {
0133         /* work was already done */
0134
0135         /* stash fids for close() later */
0136         struct cifs_fid fid = {
0137             .persistent_fid = pfid->persistent_fid,
0138             .volatile_fid = pfid->volatile_fid,
0139         };
0140
0141         /*
0142          * caller expects this func to set the fid in cfid to valid
0143          * cached root, so increment the refcount.
0144          */
0145         kref_get(&cfid->refcount);
0146
0147         mutex_unlock(&cfid->fid_mutex);
0148
0149         if (rc == 0) {
0150             /* close extra handle outside of crit sec */
0151             SMB2_close(xid, tcon, fid.persistent_fid, fid.volatile_fid);
0152         }
0153         rc = 0;
0154         goto oshr_free;
0155     }
0156
0157     /* Cached root is still invalid, continue normaly */
0158
0159     if (rc) {
0160         if (rc == -EREMCHG) {
0161             tcon->need_reconnect = true;
0162             pr_warn_once("server share %s deleted\n",
0163                      tcon->treeName);
0164         }
0165         goto oshr_exit;
0166     }
0167
0168     atomic_inc(&tcon->num_remote_opens);
0169
0170     o_rsp = (struct smb2_create_rsp *)rsp_iov[0].iov_base;
0171     oparms.fid->persistent_fid = o_rsp->PersistentFileId;
0172     oparms.fid->volatile_fid = o_rsp->VolatileFileId;
0173 #ifdef CONFIG_CIFS_DEBUG2
0174     oparms.fid->mid = le64_to_cpu(o_rsp->hdr.MessageId);
0175 #endif /* CIFS_DEBUG2 */
0176
0177     cfid->tcon = tcon;
0178     cfid->is_valid = true;
0179     cfid->dentry = dentry;
0180     dget(dentry);
0181     kref_init(&cfid->refcount);
0182
0183     /* BB TBD check to see if oplock level check can be removed below */
0184     if (o_rsp->OplockLevel == SMB2_OPLOCK_LEVEL_LEASE) {
0185         /*
0186          * See commit 2f94a3125b87. Increment the refcount when we
0187          * get a lease for root, release it if lease break occurs
0188          */
0189         kref_get(&cfid->refcount);
0190         cfid->has_lease = true;
0191         smb2_parse_contexts(server, o_rsp,
0192                 &oparms.fid->epoch,
0193                     oparms.fid->lease_key, &oplock,
0194                     NULL, NULL);
0195     } else
0196         goto oshr_exit;
0197
0198     qi_rsp = (struct smb2_query_info_rsp *)rsp_iov[1].iov_base;
0199     if (le32_to_cpu(qi_rsp->OutputBufferLength) < sizeof(struct smb2_file_all_info))
0200         goto oshr_exit;
0201     if (!smb2_validate_and_copy_iov(
0202                 le16_to_cpu(qi_rsp->OutputBufferOffset),
0203                 sizeof(struct smb2_file_all_info),
0204                 &rsp_iov[1], sizeof(struct smb2_file_all_info),
0205                 (char *)&cfid->file_all_info))
0206         cfid->file_all_info_is_valid = true;
0207
0208     cfid->time = jiffies;
0209
0210 oshr_exit:
0211     mutex_unlock(&cfid->fid_mutex);
0212 oshr_free:
0213     SMB2_open_free(&rqst[0]);
0214     SMB2_query_info_free(&rqst[1]);
0215     free_rsp_buf(resp_buftype[0], rsp_iov[0].iov_base);
0216     free_rsp_buf(resp_buftype[1], rsp_iov[1].iov_base);
0217     if (rc == 0)
0218         *ret_cfid = cfid;
0219
0220     return rc;
0221 }
0222
0223 int open_cached_dir_by_dentry(struct cifs_tcon *tcon,
0224                   struct dentry *dentry,
0225                   struct cached_fid **ret_cfid)
0226 {
0227     struct cached_fid *cfid;
0228
0229     cfid = tcon->cfid;
0230
0231     mutex_lock(&cfid->fid_mutex);
0232     if (cfid->dentry == dentry) {
0233         cifs_dbg(FYI, "found a cached root file handle by dentry\n");
0234         *ret_cfid = cfid;
0235         kref_get(&cfid->refcount);
0236         mutex_unlock(&cfid->fid_mutex);
0237         return 0;
0238     }
0239     mutex_unlock(&cfid->fid_mutex);
0240     return -ENOENT;
0241 }
0242
0243 static void
0244 smb2_close_cached_fid(struct kref *ref)
0245 {
0246     struct cached_fid *cfid = container_of(ref, struct cached_fid,
0247                            refcount);
0248     struct cached_dirent *dirent, *q;
0249
0250     if (cfid->is_valid) {
0251         cifs_dbg(FYI, "clear cached root file handle\n");
0252         SMB2_close(0, cfid->tcon, cfid->fid.persistent_fid,
0253                cfid->fid.volatile_fid);
0254     }
0255
0256     /*
0257      * We only check validity above to send SMB2_close,
0258      * but we still need to invalidate these entries
0259      * when this function is called
0260      */
0261     cfid->is_valid = false;
0262     cfid->file_all_info_is_valid = false;
0263     cfid->has_lease = false;
0264     if (cfid->dentry) {
0265         dput(cfid->dentry);
0266         cfid->dentry = NULL;
0267     }
0268     /*
0269      * Delete all cached dirent names
0270      */
0271     mutex_lock(&cfid->dirents.de_mutex);
0272     list_for_each_entry_safe(dirent, q, &cfid->dirents.entries, entry) {
0273         list_del(&dirent->entry);
0274         kfree(dirent->name);
0275         kfree(dirent);
0276     }
0277     cfid->dirents.is_valid = 0;
0278     cfid->dirents.is_failed = 0;
0279     cfid->dirents.ctx = NULL;
0280     cfid->dirents.pos = 0;
0281     mutex_unlock(&cfid->dirents.de_mutex);
0282
0283 }
0284
0285 void close_cached_dir(struct cached_fid *cfid)
0286 {
0287     mutex_lock(&cfid->fid_mutex);
0288     kref_put(&cfid->refcount, smb2_close_cached_fid);
0289     mutex_unlock(&cfid->fid_mutex);
0290 }
0291
0292 void close_cached_dir_lease_locked(struct cached_fid *cfid)
0293 {
0294     if (cfid->has_lease) {
0295         cfid->has_lease = false;
0296         kref_put(&cfid->refcount, smb2_close_cached_fid);
0297     }
0298 }
0299
0300 void close_cached_dir_lease(struct cached_fid *cfid)
0301 {
0302     mutex_lock(&cfid->fid_mutex);
0303     close_cached_dir_lease_locked(cfid);
0304     mutex_unlock(&cfid->fid_mutex);
0305 }
0306
0307 /*
0308  * Called from cifs_kill_sb when we unmount a share
0309  */
0310 void close_all_cached_dirs(struct cifs_sb_info *cifs_sb)
0311 {
0312     struct rb_root *root = &cifs_sb->tlink_tree;
0313     struct rb_node *node;
0314     struct cached_fid *cfid;
0315     struct cifs_tcon *tcon;
0316     struct tcon_link *tlink;
0317
0318     for (node = rb_first(root); node; node = rb_next(node)) {
0319         tlink = rb_entry(node, struct tcon_link, tl_rbnode);
0320         tcon = tlink_tcon(tlink);
0321         if (IS_ERR(tcon))
0322             continue;
0323         cfid = tcon->cfid;
0324         mutex_lock(&cfid->fid_mutex);
0325         if (cfid->dentry) {
0326             dput(cfid->dentry);
0327             cfid->dentry = NULL;
0328         }
0329         mutex_unlock(&cfid->fid_mutex);
0330     }
0331 }
0332
0333 /*
0334  * Invalidate and close all cached dirs when a TCON has been reset
0335  * due to a session loss.
0336  */
0337 void invalidate_all_cached_dirs(struct cifs_tcon *tcon)
0338 {
0339     mutex_lock(&tcon->cfid->fid_mutex);
0340     tcon->cfid->is_valid = false;
0341     /* cached handle is not valid, so SMB2_CLOSE won't be sent below */
0342     close_cached_dir_lease_locked(tcon->cfid);
0343     memset(&tcon->cfid->fid, 0, sizeof(struct cifs_fid));
0344     mutex_unlock(&tcon->cfid->fid_mutex);
0345 }
0346
0347 static void
0348 smb2_cached_lease_break(struct work_struct *work)
0349 {
0350     struct cached_fid *cfid = container_of(work,
0351                 struct cached_fid, lease_break);
0352
0353     close_cached_dir_lease(cfid);
0354 }
0355
0356 int cached_dir_lease_break(struct cifs_tcon *tcon, __u8 lease_key[16])
0357 {
0358     if (tcon->cfid->is_valid &&
0359         !memcmp(lease_key,
0360             tcon->cfid->fid.lease_key,
0361             SMB2_LEASE_KEY_SIZE)) {
0362         tcon->cfid->time = 0;
0363         INIT_WORK(&tcon->cfid->lease_break,
0364               smb2_cached_lease_break);
0365         queue_work(cifsiod_wq,
0366                &tcon->cfid->lease_break);
0367         return true;
0368     }
0369     return false;
0370 }
0371
0372 struct cached_fid *init_cached_dir(void)
0373 {
0374     struct cached_fid *cfid;
0375
0376     cfid = kzalloc(sizeof(*cfid), GFP_KERNEL);
0377     if (!cfid)
0378         return NULL;
0379     INIT_LIST_HEAD(&cfid->dirents.entries);
0380     mutex_init(&cfid->dirents.de_mutex);
0381     mutex_init(&cfid->fid_mutex);
0382     return cfid;
0383 }
0384
0385 void free_cached_dir(struct cifs_tcon *tcon)
0386 {
0387     kfree(tcon->cfid);
0388 }