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0001 // SPDX-License-Identifier: GPL-2.0-only
0002 /*
0003  * This file contains vfs inode ops for the 9P2000 protocol.
0004  *
0005  *  Copyright (C) 2004 by Eric Van Hensbergen <ericvh@gmail.com>
0006  *  Copyright (C) 2002 by Ron Minnich <rminnich@lanl.gov>
0007  */
0008 
0009 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
0010 
0011 #include <linux/module.h>
0012 #include <linux/errno.h>
0013 #include <linux/fs.h>
0014 #include <linux/file.h>
0015 #include <linux/pagemap.h>
0016 #include <linux/stat.h>
0017 #include <linux/string.h>
0018 #include <linux/inet.h>
0019 #include <linux/namei.h>
0020 #include <linux/idr.h>
0021 #include <linux/sched.h>
0022 #include <linux/slab.h>
0023 #include <linux/xattr.h>
0024 #include <linux/posix_acl.h>
0025 #include <net/9p/9p.h>
0026 #include <net/9p/client.h>
0027 
0028 #include "v9fs.h"
0029 #include "v9fs_vfs.h"
0030 #include "fid.h"
0031 #include "cache.h"
0032 #include "xattr.h"
0033 #include "acl.h"
0034 
0035 static const struct inode_operations v9fs_dir_inode_operations;
0036 static const struct inode_operations v9fs_dir_inode_operations_dotu;
0037 static const struct inode_operations v9fs_file_inode_operations;
0038 static const struct inode_operations v9fs_symlink_inode_operations;
0039 
0040 /**
0041  * unixmode2p9mode - convert unix mode bits to plan 9
0042  * @v9ses: v9fs session information
0043  * @mode: mode to convert
0044  *
0045  */
0046 
0047 static u32 unixmode2p9mode(struct v9fs_session_info *v9ses, umode_t mode)
0048 {
0049     int res;
0050 
0051     res = mode & 0777;
0052     if (S_ISDIR(mode))
0053         res |= P9_DMDIR;
0054     if (v9fs_proto_dotu(v9ses)) {
0055         if (v9ses->nodev == 0) {
0056             if (S_ISSOCK(mode))
0057                 res |= P9_DMSOCKET;
0058             if (S_ISFIFO(mode))
0059                 res |= P9_DMNAMEDPIPE;
0060             if (S_ISBLK(mode))
0061                 res |= P9_DMDEVICE;
0062             if (S_ISCHR(mode))
0063                 res |= P9_DMDEVICE;
0064         }
0065 
0066         if ((mode & S_ISUID) == S_ISUID)
0067             res |= P9_DMSETUID;
0068         if ((mode & S_ISGID) == S_ISGID)
0069             res |= P9_DMSETGID;
0070         if ((mode & S_ISVTX) == S_ISVTX)
0071             res |= P9_DMSETVTX;
0072     }
0073     return res;
0074 }
0075 
0076 /**
0077  * p9mode2perm- convert plan9 mode bits to unix permission bits
0078  * @v9ses: v9fs session information
0079  * @stat: p9_wstat from which mode need to be derived
0080  *
0081  */
0082 static int p9mode2perm(struct v9fs_session_info *v9ses,
0083                struct p9_wstat *stat)
0084 {
0085     int res;
0086     int mode = stat->mode;
0087 
0088     res = mode & S_IALLUGO;
0089     if (v9fs_proto_dotu(v9ses)) {
0090         if ((mode & P9_DMSETUID) == P9_DMSETUID)
0091             res |= S_ISUID;
0092 
0093         if ((mode & P9_DMSETGID) == P9_DMSETGID)
0094             res |= S_ISGID;
0095 
0096         if ((mode & P9_DMSETVTX) == P9_DMSETVTX)
0097             res |= S_ISVTX;
0098     }
0099     return res;
0100 }
0101 
0102 /**
0103  * p9mode2unixmode- convert plan9 mode bits to unix mode bits
0104  * @v9ses: v9fs session information
0105  * @stat: p9_wstat from which mode need to be derived
0106  * @rdev: major number, minor number in case of device files.
0107  *
0108  */
0109 static umode_t p9mode2unixmode(struct v9fs_session_info *v9ses,
0110                    struct p9_wstat *stat, dev_t *rdev)
0111 {
0112     int res, r;
0113     u32 mode = stat->mode;
0114 
0115     *rdev = 0;
0116     res = p9mode2perm(v9ses, stat);
0117 
0118     if ((mode & P9_DMDIR) == P9_DMDIR)
0119         res |= S_IFDIR;
0120     else if ((mode & P9_DMSYMLINK) && (v9fs_proto_dotu(v9ses)))
0121         res |= S_IFLNK;
0122     else if ((mode & P9_DMSOCKET) && (v9fs_proto_dotu(v9ses))
0123          && (v9ses->nodev == 0))
0124         res |= S_IFSOCK;
0125     else if ((mode & P9_DMNAMEDPIPE) && (v9fs_proto_dotu(v9ses))
0126          && (v9ses->nodev == 0))
0127         res |= S_IFIFO;
0128     else if ((mode & P9_DMDEVICE) && (v9fs_proto_dotu(v9ses))
0129          && (v9ses->nodev == 0)) {
0130         char type = 0;
0131         int major = -1, minor = -1;
0132 
0133         r = sscanf(stat->extension, "%c %i %i", &type, &major, &minor);
0134         if (r != 3) {
0135             p9_debug(P9_DEBUG_ERROR,
0136                  "invalid device string, umode will be bogus: %s\n",
0137                  stat->extension);
0138             return res;
0139         }
0140         switch (type) {
0141         case 'c':
0142             res |= S_IFCHR;
0143             break;
0144         case 'b':
0145             res |= S_IFBLK;
0146             break;
0147         default:
0148             p9_debug(P9_DEBUG_ERROR, "Unknown special type %c %s\n",
0149                  type, stat->extension);
0150         }
0151         *rdev = MKDEV(major, minor);
0152     } else
0153         res |= S_IFREG;
0154 
0155     return res;
0156 }
0157 
0158 /**
0159  * v9fs_uflags2omode- convert posix open flags to plan 9 mode bits
0160  * @uflags: flags to convert
0161  * @extended: if .u extensions are active
0162  */
0163 
0164 int v9fs_uflags2omode(int uflags, int extended)
0165 {
0166     int ret;
0167 
0168     ret = 0;
0169     switch (uflags&3) {
0170     default:
0171     case O_RDONLY:
0172         ret = P9_OREAD;
0173         break;
0174 
0175     case O_WRONLY:
0176         ret = P9_OWRITE;
0177         break;
0178 
0179     case O_RDWR:
0180         ret = P9_ORDWR;
0181         break;
0182     }
0183 
0184     if (extended) {
0185         if (uflags & O_EXCL)
0186             ret |= P9_OEXCL;
0187 
0188         if (uflags & O_APPEND)
0189             ret |= P9_OAPPEND;
0190     }
0191 
0192     return ret;
0193 }
0194 
0195 /**
0196  * v9fs_blank_wstat - helper function to setup a 9P stat structure
0197  * @wstat: structure to initialize
0198  *
0199  */
0200 
0201 void
0202 v9fs_blank_wstat(struct p9_wstat *wstat)
0203 {
0204     wstat->type = ~0;
0205     wstat->dev = ~0;
0206     wstat->qid.type = ~0;
0207     wstat->qid.version = ~0;
0208     *((long long *)&wstat->qid.path) = ~0;
0209     wstat->mode = ~0;
0210     wstat->atime = ~0;
0211     wstat->mtime = ~0;
0212     wstat->length = ~0;
0213     wstat->name = NULL;
0214     wstat->uid = NULL;
0215     wstat->gid = NULL;
0216     wstat->muid = NULL;
0217     wstat->n_uid = INVALID_UID;
0218     wstat->n_gid = INVALID_GID;
0219     wstat->n_muid = INVALID_UID;
0220     wstat->extension = NULL;
0221 }
0222 
0223 /**
0224  * v9fs_alloc_inode - helper function to allocate an inode
0225  * @sb: The superblock to allocate the inode from
0226  */
0227 struct inode *v9fs_alloc_inode(struct super_block *sb)
0228 {
0229     struct v9fs_inode *v9inode;
0230 
0231     v9inode = alloc_inode_sb(sb, v9fs_inode_cache, GFP_KERNEL);
0232     if (!v9inode)
0233         return NULL;
0234     v9inode->writeback_fid = NULL;
0235     v9inode->cache_validity = 0;
0236     mutex_init(&v9inode->v_mutex);
0237     return &v9inode->netfs.inode;
0238 }
0239 
0240 /**
0241  * v9fs_free_inode - destroy an inode
0242  * @inode: The inode to be freed
0243  */
0244 
0245 void v9fs_free_inode(struct inode *inode)
0246 {
0247     kmem_cache_free(v9fs_inode_cache, V9FS_I(inode));
0248 }
0249 
0250 /*
0251  * Set parameters for the netfs library
0252  */
0253 static void v9fs_set_netfs_context(struct inode *inode)
0254 {
0255     struct v9fs_inode *v9inode = V9FS_I(inode);
0256     netfs_inode_init(&v9inode->netfs, &v9fs_req_ops);
0257 }
0258 
0259 int v9fs_init_inode(struct v9fs_session_info *v9ses,
0260             struct inode *inode, umode_t mode, dev_t rdev)
0261 {
0262     int err = 0;
0263 
0264     inode_init_owner(&init_user_ns, inode, NULL, mode);
0265     inode->i_blocks = 0;
0266     inode->i_rdev = rdev;
0267     inode->i_atime = inode->i_mtime = inode->i_ctime = current_time(inode);
0268     inode->i_mapping->a_ops = &v9fs_addr_operations;
0269     inode->i_private = NULL;
0270 
0271     switch (mode & S_IFMT) {
0272     case S_IFIFO:
0273     case S_IFBLK:
0274     case S_IFCHR:
0275     case S_IFSOCK:
0276         if (v9fs_proto_dotl(v9ses)) {
0277             inode->i_op = &v9fs_file_inode_operations_dotl;
0278         } else if (v9fs_proto_dotu(v9ses)) {
0279             inode->i_op = &v9fs_file_inode_operations;
0280         } else {
0281             p9_debug(P9_DEBUG_ERROR,
0282                  "special files without extended mode\n");
0283             err = -EINVAL;
0284             goto error;
0285         }
0286         init_special_inode(inode, inode->i_mode, inode->i_rdev);
0287         break;
0288     case S_IFREG:
0289         if (v9fs_proto_dotl(v9ses)) {
0290             inode->i_op = &v9fs_file_inode_operations_dotl;
0291             if (v9ses->cache == CACHE_LOOSE ||
0292                 v9ses->cache == CACHE_FSCACHE)
0293                 inode->i_fop =
0294                     &v9fs_cached_file_operations_dotl;
0295             else if (v9ses->cache == CACHE_MMAP)
0296                 inode->i_fop = &v9fs_mmap_file_operations_dotl;
0297             else
0298                 inode->i_fop = &v9fs_file_operations_dotl;
0299         } else {
0300             inode->i_op = &v9fs_file_inode_operations;
0301             if (v9ses->cache == CACHE_LOOSE ||
0302                 v9ses->cache == CACHE_FSCACHE)
0303                 inode->i_fop =
0304                     &v9fs_cached_file_operations;
0305             else if (v9ses->cache == CACHE_MMAP)
0306                 inode->i_fop = &v9fs_mmap_file_operations;
0307             else
0308                 inode->i_fop = &v9fs_file_operations;
0309         }
0310 
0311         break;
0312     case S_IFLNK:
0313         if (!v9fs_proto_dotu(v9ses) && !v9fs_proto_dotl(v9ses)) {
0314             p9_debug(P9_DEBUG_ERROR,
0315                  "extended modes used with legacy protocol\n");
0316             err = -EINVAL;
0317             goto error;
0318         }
0319 
0320         if (v9fs_proto_dotl(v9ses))
0321             inode->i_op = &v9fs_symlink_inode_operations_dotl;
0322         else
0323             inode->i_op = &v9fs_symlink_inode_operations;
0324 
0325         break;
0326     case S_IFDIR:
0327         inc_nlink(inode);
0328         if (v9fs_proto_dotl(v9ses))
0329             inode->i_op = &v9fs_dir_inode_operations_dotl;
0330         else if (v9fs_proto_dotu(v9ses))
0331             inode->i_op = &v9fs_dir_inode_operations_dotu;
0332         else
0333             inode->i_op = &v9fs_dir_inode_operations;
0334 
0335         if (v9fs_proto_dotl(v9ses))
0336             inode->i_fop = &v9fs_dir_operations_dotl;
0337         else
0338             inode->i_fop = &v9fs_dir_operations;
0339 
0340         break;
0341     default:
0342         p9_debug(P9_DEBUG_ERROR, "BAD mode 0x%hx S_IFMT 0x%x\n",
0343              mode, mode & S_IFMT);
0344         err = -EINVAL;
0345         goto error;
0346     }
0347 
0348     v9fs_set_netfs_context(inode);
0349 error:
0350     return err;
0351 
0352 }
0353 
0354 /**
0355  * v9fs_get_inode - helper function to setup an inode
0356  * @sb: superblock
0357  * @mode: mode to setup inode with
0358  * @rdev: The device numbers to set
0359  */
0360 
0361 struct inode *v9fs_get_inode(struct super_block *sb, umode_t mode, dev_t rdev)
0362 {
0363     int err;
0364     struct inode *inode;
0365     struct v9fs_session_info *v9ses = sb->s_fs_info;
0366 
0367     p9_debug(P9_DEBUG_VFS, "super block: %p mode: %ho\n", sb, mode);
0368 
0369     inode = new_inode(sb);
0370     if (!inode) {
0371         pr_warn("%s (%d): Problem allocating inode\n",
0372             __func__, task_pid_nr(current));
0373         return ERR_PTR(-ENOMEM);
0374     }
0375     err = v9fs_init_inode(v9ses, inode, mode, rdev);
0376     if (err) {
0377         iput(inode);
0378         return ERR_PTR(err);
0379     }
0380     return inode;
0381 }
0382 
0383 /**
0384  * v9fs_evict_inode - Remove an inode from the inode cache
0385  * @inode: inode to release
0386  *
0387  */
0388 void v9fs_evict_inode(struct inode *inode)
0389 {
0390     struct v9fs_inode *v9inode = V9FS_I(inode);
0391     __le32 version;
0392 
0393     truncate_inode_pages_final(&inode->i_data);
0394     version = cpu_to_le32(v9inode->qid.version);
0395     fscache_clear_inode_writeback(v9fs_inode_cookie(v9inode), inode,
0396                       &version);
0397     clear_inode(inode);
0398     filemap_fdatawrite(&inode->i_data);
0399 
0400     fscache_relinquish_cookie(v9fs_inode_cookie(v9inode), false);
0401     /* clunk the fid stashed in writeback_fid */
0402     p9_fid_put(v9inode->writeback_fid);
0403     v9inode->writeback_fid = NULL;
0404 }
0405 
0406 static int v9fs_test_inode(struct inode *inode, void *data)
0407 {
0408     int umode;
0409     dev_t rdev;
0410     struct v9fs_inode *v9inode = V9FS_I(inode);
0411     struct p9_wstat *st = (struct p9_wstat *)data;
0412     struct v9fs_session_info *v9ses = v9fs_inode2v9ses(inode);
0413 
0414     umode = p9mode2unixmode(v9ses, st, &rdev);
0415     /* don't match inode of different type */
0416     if (inode_wrong_type(inode, umode))
0417         return 0;
0418 
0419     /* compare qid details */
0420     if (memcmp(&v9inode->qid.version,
0421            &st->qid.version, sizeof(v9inode->qid.version)))
0422         return 0;
0423 
0424     if (v9inode->qid.type != st->qid.type)
0425         return 0;
0426 
0427     if (v9inode->qid.path != st->qid.path)
0428         return 0;
0429     return 1;
0430 }
0431 
0432 static int v9fs_test_new_inode(struct inode *inode, void *data)
0433 {
0434     return 0;
0435 }
0436 
0437 static int v9fs_set_inode(struct inode *inode,  void *data)
0438 {
0439     struct v9fs_inode *v9inode = V9FS_I(inode);
0440     struct p9_wstat *st = (struct p9_wstat *)data;
0441 
0442     memcpy(&v9inode->qid, &st->qid, sizeof(st->qid));
0443     return 0;
0444 }
0445 
0446 static struct inode *v9fs_qid_iget(struct super_block *sb,
0447                    struct p9_qid *qid,
0448                    struct p9_wstat *st,
0449                    int new)
0450 {
0451     dev_t rdev;
0452     int retval;
0453     umode_t umode;
0454     unsigned long i_ino;
0455     struct inode *inode;
0456     struct v9fs_session_info *v9ses = sb->s_fs_info;
0457     int (*test)(struct inode *inode, void *data);
0458 
0459     if (new)
0460         test = v9fs_test_new_inode;
0461     else
0462         test = v9fs_test_inode;
0463 
0464     i_ino = v9fs_qid2ino(qid);
0465     inode = iget5_locked(sb, i_ino, test, v9fs_set_inode, st);
0466     if (!inode)
0467         return ERR_PTR(-ENOMEM);
0468     if (!(inode->i_state & I_NEW))
0469         return inode;
0470     /*
0471      * initialize the inode with the stat info
0472      * FIXME!! we may need support for stale inodes
0473      * later.
0474      */
0475     inode->i_ino = i_ino;
0476     umode = p9mode2unixmode(v9ses, st, &rdev);
0477     retval = v9fs_init_inode(v9ses, inode, umode, rdev);
0478     if (retval)
0479         goto error;
0480 
0481     v9fs_stat2inode(st, inode, sb, 0);
0482     v9fs_cache_inode_get_cookie(inode);
0483     unlock_new_inode(inode);
0484     return inode;
0485 error:
0486     iget_failed(inode);
0487     return ERR_PTR(retval);
0488 
0489 }
0490 
0491 struct inode *
0492 v9fs_inode_from_fid(struct v9fs_session_info *v9ses, struct p9_fid *fid,
0493             struct super_block *sb, int new)
0494 {
0495     struct p9_wstat *st;
0496     struct inode *inode = NULL;
0497 
0498     st = p9_client_stat(fid);
0499     if (IS_ERR(st))
0500         return ERR_CAST(st);
0501 
0502     inode = v9fs_qid_iget(sb, &st->qid, st, new);
0503     p9stat_free(st);
0504     kfree(st);
0505     return inode;
0506 }
0507 
0508 /**
0509  * v9fs_at_to_dotl_flags- convert Linux specific AT flags to
0510  * plan 9 AT flag.
0511  * @flags: flags to convert
0512  */
0513 static int v9fs_at_to_dotl_flags(int flags)
0514 {
0515     int rflags = 0;
0516 
0517     if (flags & AT_REMOVEDIR)
0518         rflags |= P9_DOTL_AT_REMOVEDIR;
0519 
0520     return rflags;
0521 }
0522 
0523 /**
0524  * v9fs_dec_count - helper functon to drop i_nlink.
0525  *
0526  * If a directory had nlink <= 2 (including . and ..), then we should not drop
0527  * the link count, which indicates the underlying exported fs doesn't maintain
0528  * nlink accurately. e.g.
0529  * - overlayfs sets nlink to 1 for merged dir
0530  * - ext4 (with dir_nlink feature enabled) sets nlink to 1 if a dir has more
0531  *   than EXT4_LINK_MAX (65000) links.
0532  *
0533  * @inode: inode whose nlink is being dropped
0534  */
0535 static void v9fs_dec_count(struct inode *inode)
0536 {
0537     if (!S_ISDIR(inode->i_mode) || inode->i_nlink > 2)
0538         drop_nlink(inode);
0539 }
0540 
0541 /**
0542  * v9fs_remove - helper function to remove files and directories
0543  * @dir: directory inode that is being deleted
0544  * @dentry:  dentry that is being deleted
0545  * @flags: removing a directory
0546  *
0547  */
0548 
0549 static int v9fs_remove(struct inode *dir, struct dentry *dentry, int flags)
0550 {
0551     struct inode *inode;
0552     int retval = -EOPNOTSUPP;
0553     struct p9_fid *v9fid, *dfid;
0554     struct v9fs_session_info *v9ses;
0555 
0556     p9_debug(P9_DEBUG_VFS, "inode: %p dentry: %p rmdir: %x\n",
0557          dir, dentry, flags);
0558 
0559     v9ses = v9fs_inode2v9ses(dir);
0560     inode = d_inode(dentry);
0561     dfid = v9fs_parent_fid(dentry);
0562     if (IS_ERR(dfid)) {
0563         retval = PTR_ERR(dfid);
0564         p9_debug(P9_DEBUG_VFS, "fid lookup failed %d\n", retval);
0565         return retval;
0566     }
0567     if (v9fs_proto_dotl(v9ses))
0568         retval = p9_client_unlinkat(dfid, dentry->d_name.name,
0569                         v9fs_at_to_dotl_flags(flags));
0570     p9_fid_put(dfid);
0571     if (retval == -EOPNOTSUPP) {
0572         /* Try the one based on path */
0573         v9fid = v9fs_fid_clone(dentry);
0574         if (IS_ERR(v9fid))
0575             return PTR_ERR(v9fid);
0576         retval = p9_client_remove(v9fid);
0577     }
0578     if (!retval) {
0579         /*
0580          * directories on unlink should have zero
0581          * link count
0582          */
0583         if (flags & AT_REMOVEDIR) {
0584             clear_nlink(inode);
0585             v9fs_dec_count(dir);
0586         } else
0587             v9fs_dec_count(inode);
0588 
0589         v9fs_invalidate_inode_attr(inode);
0590         v9fs_invalidate_inode_attr(dir);
0591 
0592         /* invalidate all fids associated with dentry */
0593         /* NOTE: This will not include open fids */
0594         dentry->d_op->d_release(dentry);
0595     }
0596     return retval;
0597 }
0598 
0599 /**
0600  * v9fs_create - Create a file
0601  * @v9ses: session information
0602  * @dir: directory that dentry is being created in
0603  * @dentry:  dentry that is being created
0604  * @extension: 9p2000.u extension string to support devices, etc.
0605  * @perm: create permissions
0606  * @mode: open mode
0607  *
0608  */
0609 static struct p9_fid *
0610 v9fs_create(struct v9fs_session_info *v9ses, struct inode *dir,
0611         struct dentry *dentry, char *extension, u32 perm, u8 mode)
0612 {
0613     int err;
0614     const unsigned char *name;
0615     struct p9_fid *dfid, *ofid = NULL, *fid = NULL;
0616     struct inode *inode;
0617 
0618     p9_debug(P9_DEBUG_VFS, "name %pd\n", dentry);
0619 
0620     err = 0;
0621     name = dentry->d_name.name;
0622     dfid = v9fs_parent_fid(dentry);
0623     if (IS_ERR(dfid)) {
0624         err = PTR_ERR(dfid);
0625         p9_debug(P9_DEBUG_VFS, "fid lookup failed %d\n", err);
0626         return ERR_PTR(err);
0627     }
0628 
0629     /* clone a fid to use for creation */
0630     ofid = clone_fid(dfid);
0631     if (IS_ERR(ofid)) {
0632         err = PTR_ERR(ofid);
0633         p9_debug(P9_DEBUG_VFS, "p9_client_walk failed %d\n", err);
0634         goto error;
0635     }
0636 
0637     err = p9_client_fcreate(ofid, name, perm, mode, extension);
0638     if (err < 0) {
0639         p9_debug(P9_DEBUG_VFS, "p9_client_fcreate failed %d\n", err);
0640         goto error;
0641     }
0642 
0643     if (!(perm & P9_DMLINK)) {
0644         /* now walk from the parent so we can get unopened fid */
0645         fid = p9_client_walk(dfid, 1, &name, 1);
0646         if (IS_ERR(fid)) {
0647             err = PTR_ERR(fid);
0648             p9_debug(P9_DEBUG_VFS,
0649                    "p9_client_walk failed %d\n", err);
0650             goto error;
0651         }
0652         /*
0653          * instantiate inode and assign the unopened fid to the dentry
0654          */
0655         inode = v9fs_get_new_inode_from_fid(v9ses, fid, dir->i_sb);
0656         if (IS_ERR(inode)) {
0657             err = PTR_ERR(inode);
0658             p9_debug(P9_DEBUG_VFS,
0659                    "inode creation failed %d\n", err);
0660             goto error;
0661         }
0662         v9fs_fid_add(dentry, &fid);
0663         d_instantiate(dentry, inode);
0664     }
0665     p9_fid_put(dfid);
0666     return ofid;
0667 error:
0668     p9_fid_put(dfid);
0669     p9_fid_put(ofid);
0670     p9_fid_put(fid);
0671     return ERR_PTR(err);
0672 }
0673 
0674 /**
0675  * v9fs_vfs_create - VFS hook to create a regular file
0676  * @mnt_userns: The user namespace of the mount
0677  * @dir: The parent directory
0678  * @dentry: The name of file to be created
0679  * @mode: The UNIX file mode to set
0680  * @excl: True if the file must not yet exist
0681  *
0682  * open(.., O_CREAT) is handled in v9fs_vfs_atomic_open().  This is only called
0683  * for mknod(2).
0684  *
0685  */
0686 
0687 static int
0688 v9fs_vfs_create(struct user_namespace *mnt_userns, struct inode *dir,
0689         struct dentry *dentry, umode_t mode, bool excl)
0690 {
0691     struct v9fs_session_info *v9ses = v9fs_inode2v9ses(dir);
0692     u32 perm = unixmode2p9mode(v9ses, mode);
0693     struct p9_fid *fid;
0694 
0695     /* P9_OEXCL? */
0696     fid = v9fs_create(v9ses, dir, dentry, NULL, perm, P9_ORDWR);
0697     if (IS_ERR(fid))
0698         return PTR_ERR(fid);
0699 
0700     v9fs_invalidate_inode_attr(dir);
0701     p9_fid_put(fid);
0702 
0703     return 0;
0704 }
0705 
0706 /**
0707  * v9fs_vfs_mkdir - VFS mkdir hook to create a directory
0708  * @mnt_userns: The user namespace of the mount
0709  * @dir:  inode that is being unlinked
0710  * @dentry: dentry that is being unlinked
0711  * @mode: mode for new directory
0712  *
0713  */
0714 
0715 static int v9fs_vfs_mkdir(struct user_namespace *mnt_userns, struct inode *dir,
0716               struct dentry *dentry, umode_t mode)
0717 {
0718     int err;
0719     u32 perm;
0720     struct p9_fid *fid;
0721     struct v9fs_session_info *v9ses;
0722 
0723     p9_debug(P9_DEBUG_VFS, "name %pd\n", dentry);
0724     err = 0;
0725     v9ses = v9fs_inode2v9ses(dir);
0726     perm = unixmode2p9mode(v9ses, mode | S_IFDIR);
0727     fid = v9fs_create(v9ses, dir, dentry, NULL, perm, P9_OREAD);
0728     if (IS_ERR(fid)) {
0729         err = PTR_ERR(fid);
0730         fid = NULL;
0731     } else {
0732         inc_nlink(dir);
0733         v9fs_invalidate_inode_attr(dir);
0734     }
0735 
0736     if (fid)
0737         p9_fid_put(fid);
0738 
0739     return err;
0740 }
0741 
0742 /**
0743  * v9fs_vfs_lookup - VFS lookup hook to "walk" to a new inode
0744  * @dir:  inode that is being walked from
0745  * @dentry: dentry that is being walked to?
0746  * @flags: lookup flags (unused)
0747  *
0748  */
0749 
0750 struct dentry *v9fs_vfs_lookup(struct inode *dir, struct dentry *dentry,
0751                       unsigned int flags)
0752 {
0753     struct dentry *res;
0754     struct v9fs_session_info *v9ses;
0755     struct p9_fid *dfid, *fid;
0756     struct inode *inode;
0757     const unsigned char *name;
0758 
0759     p9_debug(P9_DEBUG_VFS, "dir: %p dentry: (%pd) %p flags: %x\n",
0760          dir, dentry, dentry, flags);
0761 
0762     if (dentry->d_name.len > NAME_MAX)
0763         return ERR_PTR(-ENAMETOOLONG);
0764 
0765     v9ses = v9fs_inode2v9ses(dir);
0766     /* We can walk d_parent because we hold the dir->i_mutex */
0767     dfid = v9fs_parent_fid(dentry);
0768     if (IS_ERR(dfid))
0769         return ERR_CAST(dfid);
0770 
0771     /*
0772      * Make sure we don't use a wrong inode due to parallel
0773      * unlink. For cached mode create calls request for new
0774      * inode. But with cache disabled, lookup should do this.
0775      */
0776     name = dentry->d_name.name;
0777     fid = p9_client_walk(dfid, 1, &name, 1);
0778     p9_fid_put(dfid);
0779     if (fid == ERR_PTR(-ENOENT))
0780         inode = NULL;
0781     else if (IS_ERR(fid))
0782         inode = ERR_CAST(fid);
0783     else if (v9ses->cache == CACHE_LOOSE || v9ses->cache == CACHE_FSCACHE)
0784         inode = v9fs_get_inode_from_fid(v9ses, fid, dir->i_sb);
0785     else
0786         inode = v9fs_get_new_inode_from_fid(v9ses, fid, dir->i_sb);
0787     /*
0788      * If we had a rename on the server and a parallel lookup
0789      * for the new name, then make sure we instantiate with
0790      * the new name. ie look up for a/b, while on server somebody
0791      * moved b under k and client parallely did a lookup for
0792      * k/b.
0793      */
0794     res = d_splice_alias(inode, dentry);
0795     if (!IS_ERR(fid)) {
0796         if (!res)
0797             v9fs_fid_add(dentry, &fid);
0798         else if (!IS_ERR(res))
0799             v9fs_fid_add(res, &fid);
0800         else
0801             p9_fid_put(fid);
0802     }
0803     return res;
0804 }
0805 
0806 static int
0807 v9fs_vfs_atomic_open(struct inode *dir, struct dentry *dentry,
0808              struct file *file, unsigned int flags, umode_t mode)
0809 {
0810     int err;
0811     u32 perm;
0812     struct v9fs_inode *v9inode;
0813     struct v9fs_session_info *v9ses;
0814     struct p9_fid *fid, *inode_fid;
0815     struct dentry *res = NULL;
0816     struct inode *inode;
0817 
0818     if (d_in_lookup(dentry)) {
0819         res = v9fs_vfs_lookup(dir, dentry, 0);
0820         if (IS_ERR(res))
0821             return PTR_ERR(res);
0822 
0823         if (res)
0824             dentry = res;
0825     }
0826 
0827     /* Only creates */
0828     if (!(flags & O_CREAT) || d_really_is_positive(dentry))
0829         return finish_no_open(file, res);
0830 
0831     err = 0;
0832 
0833     v9ses = v9fs_inode2v9ses(dir);
0834     perm = unixmode2p9mode(v9ses, mode);
0835     fid = v9fs_create(v9ses, dir, dentry, NULL, perm,
0836                 v9fs_uflags2omode(flags,
0837                         v9fs_proto_dotu(v9ses)));
0838     if (IS_ERR(fid)) {
0839         err = PTR_ERR(fid);
0840         goto error;
0841     }
0842 
0843     v9fs_invalidate_inode_attr(dir);
0844     inode = d_inode(dentry);
0845     v9inode = V9FS_I(inode);
0846     mutex_lock(&v9inode->v_mutex);
0847     if ((v9ses->cache == CACHE_LOOSE || v9ses->cache == CACHE_FSCACHE) &&
0848         !v9inode->writeback_fid &&
0849         ((flags & O_ACCMODE) != O_RDONLY)) {
0850         /*
0851          * clone a fid and add it to writeback_fid
0852          * we do it during open time instead of
0853          * page dirty time via write_begin/page_mkwrite
0854          * because we want write after unlink usecase
0855          * to work.
0856          */
0857         inode_fid = v9fs_writeback_fid(dentry);
0858         if (IS_ERR(inode_fid)) {
0859             err = PTR_ERR(inode_fid);
0860             mutex_unlock(&v9inode->v_mutex);
0861             goto error;
0862         }
0863         v9inode->writeback_fid = (void *) inode_fid;
0864     }
0865     mutex_unlock(&v9inode->v_mutex);
0866     err = finish_open(file, dentry, generic_file_open);
0867     if (err)
0868         goto error;
0869 
0870     file->private_data = fid;
0871     if (v9ses->cache == CACHE_LOOSE || v9ses->cache == CACHE_FSCACHE)
0872         fscache_use_cookie(v9fs_inode_cookie(v9inode),
0873                    file->f_mode & FMODE_WRITE);
0874     v9fs_open_fid_add(inode, &fid);
0875 
0876     file->f_mode |= FMODE_CREATED;
0877 out:
0878     dput(res);
0879     return err;
0880 
0881 error:
0882     p9_fid_put(fid);
0883     goto out;
0884 }
0885 
0886 /**
0887  * v9fs_vfs_unlink - VFS unlink hook to delete an inode
0888  * @i:  inode that is being unlinked
0889  * @d: dentry that is being unlinked
0890  *
0891  */
0892 
0893 int v9fs_vfs_unlink(struct inode *i, struct dentry *d)
0894 {
0895     return v9fs_remove(i, d, 0);
0896 }
0897 
0898 /**
0899  * v9fs_vfs_rmdir - VFS unlink hook to delete a directory
0900  * @i:  inode that is being unlinked
0901  * @d: dentry that is being unlinked
0902  *
0903  */
0904 
0905 int v9fs_vfs_rmdir(struct inode *i, struct dentry *d)
0906 {
0907     return v9fs_remove(i, d, AT_REMOVEDIR);
0908 }
0909 
0910 /**
0911  * v9fs_vfs_rename - VFS hook to rename an inode
0912  * @mnt_userns: The user namespace of the mount
0913  * @old_dir:  old dir inode
0914  * @old_dentry: old dentry
0915  * @new_dir: new dir inode
0916  * @new_dentry: new dentry
0917  * @flags: RENAME_* flags
0918  *
0919  */
0920 
0921 int
0922 v9fs_vfs_rename(struct user_namespace *mnt_userns, struct inode *old_dir,
0923         struct dentry *old_dentry, struct inode *new_dir,
0924         struct dentry *new_dentry, unsigned int flags)
0925 {
0926     int retval;
0927     struct inode *old_inode;
0928     struct inode *new_inode;
0929     struct v9fs_session_info *v9ses;
0930     struct p9_fid *oldfid = NULL, *dfid = NULL;
0931     struct p9_fid *olddirfid = NULL;
0932     struct p9_fid *newdirfid = NULL;
0933     struct p9_wstat wstat;
0934 
0935     if (flags)
0936         return -EINVAL;
0937 
0938     p9_debug(P9_DEBUG_VFS, "\n");
0939     retval = 0;
0940     old_inode = d_inode(old_dentry);
0941     new_inode = d_inode(new_dentry);
0942     v9ses = v9fs_inode2v9ses(old_inode);
0943     oldfid = v9fs_fid_lookup(old_dentry);
0944     if (IS_ERR(oldfid))
0945         return PTR_ERR(oldfid);
0946 
0947     dfid = v9fs_parent_fid(old_dentry);
0948     olddirfid = clone_fid(dfid);
0949     p9_fid_put(dfid);
0950     dfid = NULL;
0951 
0952     if (IS_ERR(olddirfid)) {
0953         retval = PTR_ERR(olddirfid);
0954         goto error;
0955     }
0956 
0957     dfid = v9fs_parent_fid(new_dentry);
0958     newdirfid = clone_fid(dfid);
0959     p9_fid_put(dfid);
0960     dfid = NULL;
0961 
0962     if (IS_ERR(newdirfid)) {
0963         retval = PTR_ERR(newdirfid);
0964         goto error;
0965     }
0966 
0967     down_write(&v9ses->rename_sem);
0968     if (v9fs_proto_dotl(v9ses)) {
0969         retval = p9_client_renameat(olddirfid, old_dentry->d_name.name,
0970                         newdirfid, new_dentry->d_name.name);
0971         if (retval == -EOPNOTSUPP)
0972             retval = p9_client_rename(oldfid, newdirfid,
0973                           new_dentry->d_name.name);
0974         if (retval != -EOPNOTSUPP)
0975             goto error_locked;
0976     }
0977     if (old_dentry->d_parent != new_dentry->d_parent) {
0978         /*
0979          * 9P .u can only handle file rename in the same directory
0980          */
0981 
0982         p9_debug(P9_DEBUG_ERROR, "old dir and new dir are different\n");
0983         retval = -EXDEV;
0984         goto error_locked;
0985     }
0986     v9fs_blank_wstat(&wstat);
0987     wstat.muid = v9ses->uname;
0988     wstat.name = new_dentry->d_name.name;
0989     retval = p9_client_wstat(oldfid, &wstat);
0990 
0991 error_locked:
0992     if (!retval) {
0993         if (new_inode) {
0994             if (S_ISDIR(new_inode->i_mode))
0995                 clear_nlink(new_inode);
0996             else
0997                 v9fs_dec_count(new_inode);
0998         }
0999         if (S_ISDIR(old_inode->i_mode)) {
1000             if (!new_inode)
1001                 inc_nlink(new_dir);
1002             v9fs_dec_count(old_dir);
1003         }
1004         v9fs_invalidate_inode_attr(old_inode);
1005         v9fs_invalidate_inode_attr(old_dir);
1006         v9fs_invalidate_inode_attr(new_dir);
1007 
1008         /* successful rename */
1009         d_move(old_dentry, new_dentry);
1010     }
1011     up_write(&v9ses->rename_sem);
1012 
1013 error:
1014     p9_fid_put(newdirfid);
1015     p9_fid_put(olddirfid);
1016     p9_fid_put(oldfid);
1017     return retval;
1018 }
1019 
1020 /**
1021  * v9fs_vfs_getattr - retrieve file metadata
1022  * @mnt_userns: The user namespace of the mount
1023  * @path: Object to query
1024  * @stat: metadata structure to populate
1025  * @request_mask: Mask of STATX_xxx flags indicating the caller's interests
1026  * @flags: AT_STATX_xxx setting
1027  *
1028  */
1029 
1030 static int
1031 v9fs_vfs_getattr(struct user_namespace *mnt_userns, const struct path *path,
1032          struct kstat *stat, u32 request_mask, unsigned int flags)
1033 {
1034     struct dentry *dentry = path->dentry;
1035     struct v9fs_session_info *v9ses;
1036     struct p9_fid *fid;
1037     struct p9_wstat *st;
1038 
1039     p9_debug(P9_DEBUG_VFS, "dentry: %p\n", dentry);
1040     v9ses = v9fs_dentry2v9ses(dentry);
1041     if (v9ses->cache == CACHE_LOOSE || v9ses->cache == CACHE_FSCACHE) {
1042         generic_fillattr(&init_user_ns, d_inode(dentry), stat);
1043         return 0;
1044     }
1045     fid = v9fs_fid_lookup(dentry);
1046     if (IS_ERR(fid))
1047         return PTR_ERR(fid);
1048 
1049     st = p9_client_stat(fid);
1050     p9_fid_put(fid);
1051     if (IS_ERR(st))
1052         return PTR_ERR(st);
1053 
1054     v9fs_stat2inode(st, d_inode(dentry), dentry->d_sb, 0);
1055     generic_fillattr(&init_user_ns, d_inode(dentry), stat);
1056 
1057     p9stat_free(st);
1058     kfree(st);
1059     return 0;
1060 }
1061 
1062 /**
1063  * v9fs_vfs_setattr - set file metadata
1064  * @mnt_userns: The user namespace of the mount
1065  * @dentry: file whose metadata to set
1066  * @iattr: metadata assignment structure
1067  *
1068  */
1069 
1070 static int v9fs_vfs_setattr(struct user_namespace *mnt_userns,
1071                 struct dentry *dentry, struct iattr *iattr)
1072 {
1073     int retval, use_dentry = 0;
1074     struct inode *inode = d_inode(dentry);
1075     struct v9fs_inode *v9inode = V9FS_I(inode);
1076     struct v9fs_session_info *v9ses;
1077     struct p9_fid *fid = NULL;
1078     struct p9_wstat wstat;
1079 
1080     p9_debug(P9_DEBUG_VFS, "\n");
1081     retval = setattr_prepare(&init_user_ns, dentry, iattr);
1082     if (retval)
1083         return retval;
1084 
1085     retval = -EPERM;
1086     v9ses = v9fs_dentry2v9ses(dentry);
1087     if (iattr->ia_valid & ATTR_FILE) {
1088         fid = iattr->ia_file->private_data;
1089         WARN_ON(!fid);
1090     }
1091     if (!fid) {
1092         fid = v9fs_fid_lookup(dentry);
1093         use_dentry = 1;
1094     }
1095     if (IS_ERR(fid))
1096         return PTR_ERR(fid);
1097 
1098     v9fs_blank_wstat(&wstat);
1099     if (iattr->ia_valid & ATTR_MODE)
1100         wstat.mode = unixmode2p9mode(v9ses, iattr->ia_mode);
1101 
1102     if (iattr->ia_valid & ATTR_MTIME)
1103         wstat.mtime = iattr->ia_mtime.tv_sec;
1104 
1105     if (iattr->ia_valid & ATTR_ATIME)
1106         wstat.atime = iattr->ia_atime.tv_sec;
1107 
1108     if (iattr->ia_valid & ATTR_SIZE)
1109         wstat.length = iattr->ia_size;
1110 
1111     if (v9fs_proto_dotu(v9ses)) {
1112         if (iattr->ia_valid & ATTR_UID)
1113             wstat.n_uid = iattr->ia_uid;
1114 
1115         if (iattr->ia_valid & ATTR_GID)
1116             wstat.n_gid = iattr->ia_gid;
1117     }
1118 
1119     /* Write all dirty data */
1120     if (d_is_reg(dentry))
1121         filemap_write_and_wait(inode->i_mapping);
1122 
1123     retval = p9_client_wstat(fid, &wstat);
1124 
1125     if (use_dentry)
1126         p9_fid_put(fid);
1127 
1128     if (retval < 0)
1129         return retval;
1130 
1131     if ((iattr->ia_valid & ATTR_SIZE) &&
1132         iattr->ia_size != i_size_read(inode)) {
1133         truncate_setsize(inode, iattr->ia_size);
1134         fscache_resize_cookie(v9fs_inode_cookie(v9inode), iattr->ia_size);
1135     }
1136 
1137     v9fs_invalidate_inode_attr(inode);
1138 
1139     setattr_copy(&init_user_ns, inode, iattr);
1140     mark_inode_dirty(inode);
1141     return 0;
1142 }
1143 
1144 /**
1145  * v9fs_stat2inode - populate an inode structure with mistat info
1146  * @stat: Plan 9 metadata (mistat) structure
1147  * @inode: inode to populate
1148  * @sb: superblock of filesystem
1149  * @flags: control flags (e.g. V9FS_STAT2INODE_KEEP_ISIZE)
1150  *
1151  */
1152 
1153 void
1154 v9fs_stat2inode(struct p9_wstat *stat, struct inode *inode,
1155          struct super_block *sb, unsigned int flags)
1156 {
1157     umode_t mode;
1158     struct v9fs_session_info *v9ses = sb->s_fs_info;
1159     struct v9fs_inode *v9inode = V9FS_I(inode);
1160 
1161     set_nlink(inode, 1);
1162 
1163     inode->i_atime.tv_sec = stat->atime;
1164     inode->i_mtime.tv_sec = stat->mtime;
1165     inode->i_ctime.tv_sec = stat->mtime;
1166 
1167     inode->i_uid = v9ses->dfltuid;
1168     inode->i_gid = v9ses->dfltgid;
1169 
1170     if (v9fs_proto_dotu(v9ses)) {
1171         inode->i_uid = stat->n_uid;
1172         inode->i_gid = stat->n_gid;
1173     }
1174     if ((S_ISREG(inode->i_mode)) || (S_ISDIR(inode->i_mode))) {
1175         if (v9fs_proto_dotu(v9ses)) {
1176             unsigned int i_nlink;
1177             /*
1178              * Hadlink support got added later to the .u extension.
1179              * So there can be a server out there that doesn't
1180              * support this even with .u extension. That would
1181              * just leave us with stat->extension being an empty
1182              * string, though.
1183              */
1184             /* HARDLINKCOUNT %u */
1185             if (sscanf(stat->extension,
1186                    " HARDLINKCOUNT %u", &i_nlink) == 1)
1187                 set_nlink(inode, i_nlink);
1188         }
1189     }
1190     mode = p9mode2perm(v9ses, stat);
1191     mode |= inode->i_mode & ~S_IALLUGO;
1192     inode->i_mode = mode;
1193 
1194     if (!(flags & V9FS_STAT2INODE_KEEP_ISIZE))
1195         v9fs_i_size_write(inode, stat->length);
1196     /* not real number of blocks, but 512 byte ones ... */
1197     inode->i_blocks = (stat->length + 512 - 1) >> 9;
1198     v9inode->cache_validity &= ~V9FS_INO_INVALID_ATTR;
1199 }
1200 
1201 /**
1202  * v9fs_qid2ino - convert qid into inode number
1203  * @qid: qid to hash
1204  *
1205  * BUG: potential for inode number collisions?
1206  */
1207 
1208 ino_t v9fs_qid2ino(struct p9_qid *qid)
1209 {
1210     u64 path = qid->path + 2;
1211     ino_t i = 0;
1212 
1213     if (sizeof(ino_t) == sizeof(path))
1214         memcpy(&i, &path, sizeof(ino_t));
1215     else
1216         i = (ino_t) (path ^ (path >> 32));
1217 
1218     return i;
1219 }
1220 
1221 /**
1222  * v9fs_vfs_get_link - follow a symlink path
1223  * @dentry: dentry for symlink
1224  * @inode: inode for symlink
1225  * @done: delayed call for when we are done with the return value
1226  */
1227 
1228 static const char *v9fs_vfs_get_link(struct dentry *dentry,
1229                      struct inode *inode,
1230                      struct delayed_call *done)
1231 {
1232     struct v9fs_session_info *v9ses;
1233     struct p9_fid *fid;
1234     struct p9_wstat *st;
1235     char *res;
1236 
1237     if (!dentry)
1238         return ERR_PTR(-ECHILD);
1239 
1240     v9ses = v9fs_dentry2v9ses(dentry);
1241     if (!v9fs_proto_dotu(v9ses))
1242         return ERR_PTR(-EBADF);
1243 
1244     p9_debug(P9_DEBUG_VFS, "%pd\n", dentry);
1245     fid = v9fs_fid_lookup(dentry);
1246 
1247     if (IS_ERR(fid))
1248         return ERR_CAST(fid);
1249 
1250     st = p9_client_stat(fid);
1251     p9_fid_put(fid);
1252     if (IS_ERR(st))
1253         return ERR_CAST(st);
1254 
1255     if (!(st->mode & P9_DMSYMLINK)) {
1256         p9stat_free(st);
1257         kfree(st);
1258         return ERR_PTR(-EINVAL);
1259     }
1260     res = st->extension;
1261     st->extension = NULL;
1262     if (strlen(res) >= PATH_MAX)
1263         res[PATH_MAX - 1] = '\0';
1264 
1265     p9stat_free(st);
1266     kfree(st);
1267     set_delayed_call(done, kfree_link, res);
1268     return res;
1269 }
1270 
1271 /**
1272  * v9fs_vfs_mkspecial - create a special file
1273  * @dir: inode to create special file in
1274  * @dentry: dentry to create
1275  * @perm: mode to create special file
1276  * @extension: 9p2000.u format extension string representing special file
1277  *
1278  */
1279 
1280 static int v9fs_vfs_mkspecial(struct inode *dir, struct dentry *dentry,
1281     u32 perm, const char *extension)
1282 {
1283     struct p9_fid *fid;
1284     struct v9fs_session_info *v9ses;
1285 
1286     v9ses = v9fs_inode2v9ses(dir);
1287     if (!v9fs_proto_dotu(v9ses)) {
1288         p9_debug(P9_DEBUG_ERROR, "not extended\n");
1289         return -EPERM;
1290     }
1291 
1292     fid = v9fs_create(v9ses, dir, dentry, (char *) extension, perm,
1293                                 P9_OREAD);
1294     if (IS_ERR(fid))
1295         return PTR_ERR(fid);
1296 
1297     v9fs_invalidate_inode_attr(dir);
1298     p9_fid_put(fid);
1299     return 0;
1300 }
1301 
1302 /**
1303  * v9fs_vfs_symlink - helper function to create symlinks
1304  * @mnt_userns: The user namespace of the mount
1305  * @dir: directory inode containing symlink
1306  * @dentry: dentry for symlink
1307  * @symname: symlink data
1308  *
1309  * See Also: 9P2000.u RFC for more information
1310  *
1311  */
1312 
1313 static int
1314 v9fs_vfs_symlink(struct user_namespace *mnt_userns, struct inode *dir,
1315          struct dentry *dentry, const char *symname)
1316 {
1317     p9_debug(P9_DEBUG_VFS, " %lu,%pd,%s\n",
1318          dir->i_ino, dentry, symname);
1319 
1320     return v9fs_vfs_mkspecial(dir, dentry, P9_DMSYMLINK, symname);
1321 }
1322 
1323 #define U32_MAX_DIGITS 10
1324 
1325 /**
1326  * v9fs_vfs_link - create a hardlink
1327  * @old_dentry: dentry for file to link to
1328  * @dir: inode destination for new link
1329  * @dentry: dentry for link
1330  *
1331  */
1332 
1333 static int
1334 v9fs_vfs_link(struct dentry *old_dentry, struct inode *dir,
1335           struct dentry *dentry)
1336 {
1337     int retval;
1338     char name[1 + U32_MAX_DIGITS + 2]; /* sign + number + \n + \0 */
1339     struct p9_fid *oldfid;
1340 
1341     p9_debug(P9_DEBUG_VFS, " %lu,%pd,%pd\n",
1342          dir->i_ino, dentry, old_dentry);
1343 
1344     oldfid = v9fs_fid_clone(old_dentry);
1345     if (IS_ERR(oldfid))
1346         return PTR_ERR(oldfid);
1347 
1348     sprintf(name, "%d\n", oldfid->fid);
1349     retval = v9fs_vfs_mkspecial(dir, dentry, P9_DMLINK, name);
1350     if (!retval) {
1351         v9fs_refresh_inode(oldfid, d_inode(old_dentry));
1352         v9fs_invalidate_inode_attr(dir);
1353     }
1354     p9_fid_put(oldfid);
1355     return retval;
1356 }
1357 
1358 /**
1359  * v9fs_vfs_mknod - create a special file
1360  * @mnt_userns: The user namespace of the mount
1361  * @dir: inode destination for new link
1362  * @dentry: dentry for file
1363  * @mode: mode for creation
1364  * @rdev: device associated with special file
1365  *
1366  */
1367 
1368 static int
1369 v9fs_vfs_mknod(struct user_namespace *mnt_userns, struct inode *dir,
1370            struct dentry *dentry, umode_t mode, dev_t rdev)
1371 {
1372     struct v9fs_session_info *v9ses = v9fs_inode2v9ses(dir);
1373     int retval;
1374     char name[2 + U32_MAX_DIGITS + 1 + U32_MAX_DIGITS + 1];
1375     u32 perm;
1376 
1377     p9_debug(P9_DEBUG_VFS, " %lu,%pd mode: %x MAJOR: %u MINOR: %u\n",
1378          dir->i_ino, dentry, mode,
1379          MAJOR(rdev), MINOR(rdev));
1380 
1381     /* build extension */
1382     if (S_ISBLK(mode))
1383         sprintf(name, "b %u %u", MAJOR(rdev), MINOR(rdev));
1384     else if (S_ISCHR(mode))
1385         sprintf(name, "c %u %u", MAJOR(rdev), MINOR(rdev));
1386     else
1387         *name = 0;
1388 
1389     perm = unixmode2p9mode(v9ses, mode);
1390     retval = v9fs_vfs_mkspecial(dir, dentry, perm, name);
1391 
1392     return retval;
1393 }
1394 
1395 int v9fs_refresh_inode(struct p9_fid *fid, struct inode *inode)
1396 {
1397     int umode;
1398     dev_t rdev;
1399     struct p9_wstat *st;
1400     struct v9fs_session_info *v9ses;
1401     unsigned int flags;
1402 
1403     v9ses = v9fs_inode2v9ses(inode);
1404     st = p9_client_stat(fid);
1405     if (IS_ERR(st))
1406         return PTR_ERR(st);
1407     /*
1408      * Don't update inode if the file type is different
1409      */
1410     umode = p9mode2unixmode(v9ses, st, &rdev);
1411     if (inode_wrong_type(inode, umode))
1412         goto out;
1413 
1414     /*
1415      * We don't want to refresh inode->i_size,
1416      * because we may have cached data
1417      */
1418     flags = (v9ses->cache == CACHE_LOOSE || v9ses->cache == CACHE_FSCACHE) ?
1419         V9FS_STAT2INODE_KEEP_ISIZE : 0;
1420     v9fs_stat2inode(st, inode, inode->i_sb, flags);
1421 out:
1422     p9stat_free(st);
1423     kfree(st);
1424     return 0;
1425 }
1426 
1427 static const struct inode_operations v9fs_dir_inode_operations_dotu = {
1428     .create = v9fs_vfs_create,
1429     .lookup = v9fs_vfs_lookup,
1430     .atomic_open = v9fs_vfs_atomic_open,
1431     .symlink = v9fs_vfs_symlink,
1432     .link = v9fs_vfs_link,
1433     .unlink = v9fs_vfs_unlink,
1434     .mkdir = v9fs_vfs_mkdir,
1435     .rmdir = v9fs_vfs_rmdir,
1436     .mknod = v9fs_vfs_mknod,
1437     .rename = v9fs_vfs_rename,
1438     .getattr = v9fs_vfs_getattr,
1439     .setattr = v9fs_vfs_setattr,
1440 };
1441 
1442 static const struct inode_operations v9fs_dir_inode_operations = {
1443     .create = v9fs_vfs_create,
1444     .lookup = v9fs_vfs_lookup,
1445     .atomic_open = v9fs_vfs_atomic_open,
1446     .unlink = v9fs_vfs_unlink,
1447     .mkdir = v9fs_vfs_mkdir,
1448     .rmdir = v9fs_vfs_rmdir,
1449     .mknod = v9fs_vfs_mknod,
1450     .rename = v9fs_vfs_rename,
1451     .getattr = v9fs_vfs_getattr,
1452     .setattr = v9fs_vfs_setattr,
1453 };
1454 
1455 static const struct inode_operations v9fs_file_inode_operations = {
1456     .getattr = v9fs_vfs_getattr,
1457     .setattr = v9fs_vfs_setattr,
1458 };
1459 
1460 static const struct inode_operations v9fs_symlink_inode_operations = {
1461     .get_link = v9fs_vfs_get_link,
1462     .getattr = v9fs_vfs_getattr,
1463     .setattr = v9fs_vfs_setattr,
1464 };
1465
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