linux/fs/ceph/locks.c
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   1#include <linux/ceph/ceph_debug.h>
   2
   3#include <linux/file.h>
   4#include <linux/namei.h>
   5
   6#include "super.h"
   7#include "mds_client.h"
   8#include <linux/ceph/pagelist.h>
   9
  10/**
  11 * Implement fcntl and flock locking functions.
  12 */
  13static int ceph_lock_message(u8 lock_type, u16 operation, struct file *file,
  14                             int cmd, u8 wait, struct file_lock *fl)
  15{
  16        struct inode *inode = file->f_dentry->d_inode;
  17        struct ceph_mds_client *mdsc =
  18                ceph_sb_to_client(inode->i_sb)->mdsc;
  19        struct ceph_mds_request *req;
  20        int err;
  21        u64 length = 0;
  22
  23        req = ceph_mdsc_create_request(mdsc, operation, USE_AUTH_MDS);
  24        if (IS_ERR(req))
  25                return PTR_ERR(req);
  26        req->r_inode = inode;
  27        ihold(inode);
  28
  29        /* mds requires start and length rather than start and end */
  30        if (LLONG_MAX == fl->fl_end)
  31                length = 0;
  32        else
  33                length = fl->fl_end - fl->fl_start + 1;
  34
  35        dout("ceph_lock_message: rule: %d, op: %d, pid: %llu, start: %llu, "
  36             "length: %llu, wait: %d, type: %d", (int)lock_type,
  37             (int)operation, (u64)fl->fl_pid, fl->fl_start,
  38             length, wait, fl->fl_type);
  39
  40        req->r_args.filelock_change.rule = lock_type;
  41        req->r_args.filelock_change.type = cmd;
  42        req->r_args.filelock_change.pid = cpu_to_le64((u64)fl->fl_pid);
  43        /* This should be adjusted, but I'm not sure if
  44           namespaces actually get id numbers*/
  45        req->r_args.filelock_change.pid_namespace =
  46                cpu_to_le64((u64)(unsigned long)fl->fl_nspid);
  47        req->r_args.filelock_change.start = cpu_to_le64(fl->fl_start);
  48        req->r_args.filelock_change.length = cpu_to_le64(length);
  49        req->r_args.filelock_change.wait = wait;
  50
  51        err = ceph_mdsc_do_request(mdsc, inode, req);
  52
  53        if ( operation == CEPH_MDS_OP_GETFILELOCK){
  54                fl->fl_pid = le64_to_cpu(req->r_reply_info.filelock_reply->pid);
  55                if (CEPH_LOCK_SHARED == req->r_reply_info.filelock_reply->type)
  56                        fl->fl_type = F_RDLCK;
  57                else if (CEPH_LOCK_EXCL == req->r_reply_info.filelock_reply->type)
  58                        fl->fl_type = F_WRLCK;
  59                else
  60                        fl->fl_type = F_UNLCK;
  61
  62                fl->fl_start = le64_to_cpu(req->r_reply_info.filelock_reply->start);
  63                length = le64_to_cpu(req->r_reply_info.filelock_reply->start) +
  64                                                 le64_to_cpu(req->r_reply_info.filelock_reply->length);
  65                if (length >= 1)
  66                        fl->fl_end = length -1;
  67                else
  68                        fl->fl_end = 0;
  69
  70        }
  71        ceph_mdsc_put_request(req);
  72        dout("ceph_lock_message: rule: %d, op: %d, pid: %llu, start: %llu, "
  73             "length: %llu, wait: %d, type: %d, err code %d", (int)lock_type,
  74             (int)operation, (u64)fl->fl_pid, fl->fl_start,
  75             length, wait, fl->fl_type, err);
  76        return err;
  77}
  78
  79/**
  80 * Attempt to set an fcntl lock.
  81 * For now, this just goes away to the server. Later it may be more awesome.
  82 */
  83int ceph_lock(struct file *file, int cmd, struct file_lock *fl)
  84{
  85        u8 lock_cmd;
  86        int err;
  87        u8 wait = 0;
  88        u16 op = CEPH_MDS_OP_SETFILELOCK;
  89
  90        fl->fl_nspid = get_pid(task_tgid(current));
  91        dout("ceph_lock, fl_pid:%d", fl->fl_pid);
  92
  93        /* set wait bit as appropriate, then make command as Ceph expects it*/
  94        if (F_SETLKW == cmd)
  95                wait = 1;
  96        if (F_GETLK == cmd)
  97                op = CEPH_MDS_OP_GETFILELOCK;
  98
  99        if (F_RDLCK == fl->fl_type)
 100                lock_cmd = CEPH_LOCK_SHARED;
 101        else if (F_WRLCK == fl->fl_type)
 102                lock_cmd = CEPH_LOCK_EXCL;
 103        else
 104                lock_cmd = CEPH_LOCK_UNLOCK;
 105
 106        err = ceph_lock_message(CEPH_LOCK_FCNTL, op, file, lock_cmd, wait, fl);
 107        if (!err) {
 108                if ( op != CEPH_MDS_OP_GETFILELOCK ){
 109                        dout("mds locked, locking locally");
 110                        err = posix_lock_file(file, fl, NULL);
 111                        if (err && (CEPH_MDS_OP_SETFILELOCK == op)) {
 112                                /* undo! This should only happen if
 113                                 * the kernel detects local
 114                                 * deadlock. */
 115                                ceph_lock_message(CEPH_LOCK_FCNTL, op, file,
 116                                                  CEPH_LOCK_UNLOCK, 0, fl);
 117                                dout("got %d on posix_lock_file, undid lock",
 118                                     err);
 119                        }
 120                }
 121
 122        } else if (err == -ERESTARTSYS) {
 123                dout("undoing lock\n");
 124                ceph_lock_message(CEPH_LOCK_FCNTL, op, file,
 125                                  CEPH_LOCK_UNLOCK, 0, fl);
 126        }
 127        return err;
 128}
 129
 130int ceph_flock(struct file *file, int cmd, struct file_lock *fl)
 131{
 132        u8 lock_cmd;
 133        int err;
 134        u8 wait = 1;
 135
 136        fl->fl_nspid = get_pid(task_tgid(current));
 137        dout("ceph_flock, fl_pid:%d", fl->fl_pid);
 138
 139        /* set wait bit, then clear it out of cmd*/
 140        if (cmd & LOCK_NB)
 141                wait = 0;
 142        cmd = cmd & (LOCK_SH | LOCK_EX | LOCK_UN);
 143        /* set command sequence that Ceph wants to see:
 144           shared lock, exclusive lock, or unlock */
 145        if (LOCK_SH == cmd)
 146                lock_cmd = CEPH_LOCK_SHARED;
 147        else if (LOCK_EX == cmd)
 148                lock_cmd = CEPH_LOCK_EXCL;
 149        else
 150                lock_cmd = CEPH_LOCK_UNLOCK;
 151
 152        err = ceph_lock_message(CEPH_LOCK_FLOCK, CEPH_MDS_OP_SETFILELOCK,
 153                                file, lock_cmd, wait, fl);
 154        if (!err) {
 155                err = flock_lock_file_wait(file, fl);
 156                if (err) {
 157                        ceph_lock_message(CEPH_LOCK_FLOCK,
 158                                          CEPH_MDS_OP_SETFILELOCK,
 159                                          file, CEPH_LOCK_UNLOCK, 0, fl);
 160                        dout("got %d on flock_lock_file_wait, undid lock", err);
 161                }
 162        } else if (err == -ERESTARTSYS) {
 163                dout("undoing lock\n");
 164                ceph_lock_message(CEPH_LOCK_FLOCK,
 165                                  CEPH_MDS_OP_SETFILELOCK,
 166                                  file, CEPH_LOCK_UNLOCK, 0, fl);
 167        }
 168        return err;
 169}
 170
 171/**
 172 * Must be called with BKL already held. Fills in the passed
 173 * counter variables, so you can prepare pagelist metadata before calling
 174 * ceph_encode_locks.
 175 */
 176void ceph_count_locks(struct inode *inode, int *fcntl_count, int *flock_count)
 177{
 178        struct file_lock *lock;
 179
 180        *fcntl_count = 0;
 181        *flock_count = 0;
 182
 183        for (lock = inode->i_flock; lock != NULL; lock = lock->fl_next) {
 184                if (lock->fl_flags & FL_POSIX)
 185                        ++(*fcntl_count);
 186                else if (lock->fl_flags & FL_FLOCK)
 187                        ++(*flock_count);
 188        }
 189        dout("counted %d flock locks and %d fcntl locks",
 190             *flock_count, *fcntl_count);
 191}
 192
 193/**
 194 * Encode the flock and fcntl locks for the given inode into the pagelist.
 195 * Format is: #fcntl locks, sequential fcntl locks, #flock locks,
 196 * sequential flock locks.
 197 * Must be called with lock_flocks() already held.
 198 * If we encounter more of a specific lock type than expected,
 199 * we return the value 1.
 200 */
 201int ceph_encode_locks(struct inode *inode, struct ceph_pagelist *pagelist,
 202                      int num_fcntl_locks, int num_flock_locks)
 203{
 204        struct file_lock *lock;
 205        struct ceph_filelock cephlock;
 206        int err = 0;
 207        int seen_fcntl = 0;
 208        int seen_flock = 0;
 209
 210        dout("encoding %d flock and %d fcntl locks", num_flock_locks,
 211             num_fcntl_locks);
 212        err = ceph_pagelist_append(pagelist, &num_fcntl_locks, sizeof(u32));
 213        if (err)
 214                goto fail;
 215        for (lock = inode->i_flock; lock != NULL; lock = lock->fl_next) {
 216                if (lock->fl_flags & FL_POSIX) {
 217                        ++seen_fcntl;
 218                        if (seen_fcntl > num_fcntl_locks) {
 219                                err = -ENOSPC;
 220                                goto fail;
 221                        }
 222                        err = lock_to_ceph_filelock(lock, &cephlock);
 223                        if (err)
 224                                goto fail;
 225                        err = ceph_pagelist_append(pagelist, &cephlock,
 226                                           sizeof(struct ceph_filelock));
 227                }
 228                if (err)
 229                        goto fail;
 230        }
 231
 232        err = ceph_pagelist_append(pagelist, &num_flock_locks, sizeof(u32));
 233        if (err)
 234                goto fail;
 235        for (lock = inode->i_flock; lock != NULL; lock = lock->fl_next) {
 236                if (lock->fl_flags & FL_FLOCK) {
 237                        ++seen_flock;
 238                        if (seen_flock > num_flock_locks) {
 239                                err = -ENOSPC;
 240                                goto fail;
 241                        }
 242                        err = lock_to_ceph_filelock(lock, &cephlock);
 243                        if (err)
 244                                goto fail;
 245                        err = ceph_pagelist_append(pagelist, &cephlock,
 246                                           sizeof(struct ceph_filelock));
 247                }
 248                if (err)
 249                        goto fail;
 250        }
 251fail:
 252        return err;
 253}
 254
 255/*
 256 * Given a pointer to a lock, convert it to a ceph filelock
 257 */
 258int lock_to_ceph_filelock(struct file_lock *lock,
 259                          struct ceph_filelock *cephlock)
 260{
 261        int err = 0;
 262
 263        cephlock->start = cpu_to_le64(lock->fl_start);
 264        cephlock->length = cpu_to_le64(lock->fl_end - lock->fl_start + 1);
 265        cephlock->client = cpu_to_le64(0);
 266        cephlock->pid = cpu_to_le64(lock->fl_pid);
 267        cephlock->pid_namespace =
 268                cpu_to_le64((u64)(unsigned long)lock->fl_nspid);
 269
 270        switch (lock->fl_type) {
 271        case F_RDLCK:
 272                cephlock->type = CEPH_LOCK_SHARED;
 273                break;
 274        case F_WRLCK:
 275                cephlock->type = CEPH_LOCK_EXCL;
 276                break;
 277        case F_UNLCK:
 278                cephlock->type = CEPH_LOCK_UNLOCK;
 279                break;
 280        default:
 281                dout("Have unknown lock type %d", lock->fl_type);
 282                err = -EINVAL;
 283        }
 284
 285        return err;
 286}
 287
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