xref: /openbmc/qemu/hw/9pfs/cofile.c (revision 36ebc7db)
1 /*
2  * 9p backend
3  *
4  * Copyright IBM, Corp. 2011
5  *
6  * Authors:
7  *  Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
8  *
9  * This work is licensed under the terms of the GNU GPL, version 2.  See
10  * the COPYING file in the top-level directory.
11  *
12  */
13 
14 /*
15  * Not so fast! You might want to read the 9p developer docs first:
16  * https://wiki.qemu.org/Documentation/9p
17  */
18 
19 #include "qemu/osdep.h"
20 #include "fsdev/qemu-fsdev.h"
21 #include "qemu/thread.h"
22 #include "qemu/main-loop.h"
23 #include "coth.h"
24 
25 int coroutine_fn v9fs_co_st_gen(V9fsPDU *pdu, V9fsPath *path, mode_t st_mode,
26                                 V9fsStatDotl *v9stat)
27 {
28     int err = 0;
29     V9fsState *s = pdu->s;
30 
31     if (v9fs_request_cancelled(pdu)) {
32         return -EINTR;
33     }
34     if (s->ctx.exops.get_st_gen) {
35         v9fs_path_read_lock(s);
36         v9fs_co_run_in_worker(
37             {
38                 err = s->ctx.exops.get_st_gen(&s->ctx, path, st_mode,
39                                               &v9stat->st_gen);
40                 if (err < 0) {
41                     err = -errno;
42                 }
43             });
44         v9fs_path_unlock(s);
45     }
46     return err;
47 }
48 
49 int coroutine_fn v9fs_co_lstat(V9fsPDU *pdu, V9fsPath *path, struct stat *stbuf)
50 {
51     int err;
52     V9fsState *s = pdu->s;
53 
54     if (v9fs_request_cancelled(pdu)) {
55         return -EINTR;
56     }
57     v9fs_path_read_lock(s);
58     v9fs_co_run_in_worker(
59         {
60             err = s->ops->lstat(&s->ctx, path, stbuf);
61             if (err < 0) {
62                 err = -errno;
63             }
64         });
65     v9fs_path_unlock(s);
66     return err;
67 }
68 
69 int coroutine_fn v9fs_co_fstat(V9fsPDU *pdu, V9fsFidState *fidp,
70                                struct stat *stbuf)
71 {
72     int err;
73     V9fsState *s = pdu->s;
74 
75     if (v9fs_request_cancelled(pdu)) {
76         return -EINTR;
77     }
78     v9fs_co_run_in_worker(
79         {
80             err = s->ops->fstat(&s->ctx, fidp->fid_type, &fidp->fs, stbuf);
81             if (err < 0) {
82                 err = -errno;
83             }
84         });
85     /*
86      * Some FS driver (local:mapped-file) can't support fetching attributes
87      * using file descriptor. Use Path name in that case.
88      */
89     if (err == -EOPNOTSUPP) {
90         err = v9fs_co_lstat(pdu, &fidp->path, stbuf);
91         if (err == -ENOENT) {
92             /*
93              * fstat on an unlinked file. Work with partial results
94              * returned from s->ops->fstat
95              */
96             err = 0;
97         }
98     }
99     return err;
100 }
101 
102 int coroutine_fn v9fs_co_open(V9fsPDU *pdu, V9fsFidState *fidp, int flags)
103 {
104     int err;
105     V9fsState *s = pdu->s;
106 
107     if (v9fs_request_cancelled(pdu)) {
108         return -EINTR;
109     }
110     v9fs_path_read_lock(s);
111     v9fs_co_run_in_worker(
112         {
113             err = s->ops->open(&s->ctx, &fidp->path, flags, &fidp->fs);
114             if (err == -1) {
115                 err = -errno;
116             } else {
117                 err = 0;
118             }
119         });
120     v9fs_path_unlock(s);
121     if (!err) {
122         total_open_fd++;
123         if (total_open_fd > open_fd_hw) {
124             v9fs_reclaim_fd(pdu);
125         }
126     }
127     return err;
128 }
129 
130 int coroutine_fn v9fs_co_open2(V9fsPDU *pdu, V9fsFidState *fidp,
131                                V9fsString *name, gid_t gid, int flags, int mode,
132                                struct stat *stbuf)
133 {
134     int err;
135     FsCred cred;
136     V9fsPath path;
137     V9fsState *s = pdu->s;
138 
139     if (v9fs_request_cancelled(pdu)) {
140         return -EINTR;
141     }
142     cred_init(&cred);
143     cred.fc_mode = mode & 07777;
144     cred.fc_uid = fidp->uid;
145     cred.fc_gid = gid;
146     /*
147      * Hold the directory fid lock so that directory path name
148      * don't change. Take the write lock to be sure this fid
149      * cannot be used by another operation.
150      */
151     v9fs_path_write_lock(s);
152     v9fs_co_run_in_worker(
153         {
154             err = s->ops->open2(&s->ctx, &fidp->path,
155                                 name->data, flags, &cred, &fidp->fs);
156             if (err < 0) {
157                 err = -errno;
158             } else {
159                 v9fs_path_init(&path);
160                 err = v9fs_name_to_path(s, &fidp->path, name->data, &path);
161                 if (!err) {
162                     err = s->ops->lstat(&s->ctx, &path, stbuf);
163                     if (err < 0) {
164                         err = -errno;
165                         s->ops->close(&s->ctx, &fidp->fs);
166                     } else {
167                         v9fs_path_copy(&fidp->path, &path);
168                     }
169                 } else {
170                     s->ops->close(&s->ctx, &fidp->fs);
171                 }
172                 v9fs_path_free(&path);
173             }
174         });
175     v9fs_path_unlock(s);
176     if (!err) {
177         total_open_fd++;
178         if (total_open_fd > open_fd_hw) {
179             v9fs_reclaim_fd(pdu);
180         }
181     }
182     return err;
183 }
184 
185 int coroutine_fn v9fs_co_close(V9fsPDU *pdu, V9fsFidOpenState *fs)
186 {
187     int err;
188     V9fsState *s = pdu->s;
189 
190     if (v9fs_request_cancelled(pdu)) {
191         return -EINTR;
192     }
193     v9fs_co_run_in_worker(
194         {
195             err = s->ops->close(&s->ctx, fs);
196             if (err < 0) {
197                 err = -errno;
198             }
199         });
200     if (!err) {
201         total_open_fd--;
202     }
203     return err;
204 }
205 
206 int coroutine_fn v9fs_co_fsync(V9fsPDU *pdu, V9fsFidState *fidp, int datasync)
207 {
208     int err;
209     V9fsState *s = pdu->s;
210 
211     if (v9fs_request_cancelled(pdu)) {
212         return -EINTR;
213     }
214     v9fs_co_run_in_worker(
215         {
216             err = s->ops->fsync(&s->ctx, fidp->fid_type, &fidp->fs, datasync);
217             if (err < 0) {
218                 err = -errno;
219             }
220         });
221     return err;
222 }
223 
224 int coroutine_fn v9fs_co_link(V9fsPDU *pdu, V9fsFidState *oldfid,
225                               V9fsFidState *newdirfid, V9fsString *name)
226 {
227     int err;
228     V9fsState *s = pdu->s;
229 
230     if (v9fs_request_cancelled(pdu)) {
231         return -EINTR;
232     }
233     v9fs_path_read_lock(s);
234     v9fs_co_run_in_worker(
235         {
236             err = s->ops->link(&s->ctx, &oldfid->path,
237                                &newdirfid->path, name->data);
238             if (err < 0) {
239                 err = -errno;
240             }
241         });
242     v9fs_path_unlock(s);
243     return err;
244 }
245 
246 int coroutine_fn v9fs_co_pwritev(V9fsPDU *pdu, V9fsFidState *fidp,
247                                  struct iovec *iov, int iovcnt, int64_t offset)
248 {
249     int err;
250     V9fsState *s = pdu->s;
251 
252     if (v9fs_request_cancelled(pdu)) {
253         return -EINTR;
254     }
255     fsdev_co_throttle_request(s->ctx.fst, true, iov, iovcnt);
256     v9fs_co_run_in_worker(
257         {
258             err = s->ops->pwritev(&s->ctx, &fidp->fs, iov, iovcnt, offset);
259             if (err < 0) {
260                 err = -errno;
261             }
262         });
263     return err;
264 }
265 
266 int coroutine_fn v9fs_co_preadv(V9fsPDU *pdu, V9fsFidState *fidp,
267                                 struct iovec *iov, int iovcnt, int64_t offset)
268 {
269     int err;
270     V9fsState *s = pdu->s;
271 
272     if (v9fs_request_cancelled(pdu)) {
273         return -EINTR;
274     }
275     fsdev_co_throttle_request(s->ctx.fst, false, iov, iovcnt);
276     v9fs_co_run_in_worker(
277         {
278             err = s->ops->preadv(&s->ctx, &fidp->fs, iov, iovcnt, offset);
279             if (err < 0) {
280                 err = -errno;
281             }
282         });
283     return err;
284 }
285