1 /*-
2 * Copyright 2021 Toomas Soome <[email protected]>
3 *
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions
6 * are met:
7 * 1. Redistributions of source code must retain the above copyright
8 * notice, this list of conditions and the following disclaimer.
9 * 2. Redistributions in binary form must reproduce the above copyright
10 * notice, this list of conditions and the following disclaimer in the
11 * documentation and/or other materials provided with the distribution.
12 *
13 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
14 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
15 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
16 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
17 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
18 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
19 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
20 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
21 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
22 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
23 * SUCH DAMAGE.
24 */
25
26 #include <sys/cdefs.h>
27 __FBSDID("$FreeBSD$");
28
29 #include <stand.h>
30 #include <sys/queue.h>
31
32 /*
33 * While setting "currdev" environment variable, alse "mount" the
34 * new root file system. This is done to hold disk device open
35 * in between file accesses, and thus preserve block cache for
36 * this device. Additionally, this allows us to optimize filesystem
37 * access by sharing filesystem metadata (like superblock).
38 */
39
40 typedef STAILQ_HEAD(mnt_info_list, mnt_info) mnt_info_list_t;
41
42 typedef struct mnt_info {
43 STAILQ_ENTRY(mnt_info) mnt_link; /* link in mount list */
44 const struct fs_ops *mnt_fs;
45 char *mnt_dev;
46 char *mnt_path;
47 unsigned mnt_refcount;
48 void *mnt_data; /* Private state */
49 } mnt_info_t;
50
51 /* list of mounted filesystems. */
52 static mnt_info_list_t mnt_list = STAILQ_HEAD_INITIALIZER(mnt_list);
53
54 static void
free_mnt(mnt_info_t * mnt)55 free_mnt(mnt_info_t *mnt)
56 {
57 free(mnt->mnt_dev);
58 free(mnt->mnt_path);
59 free(mnt);
60 }
61
62 static int
add_mnt_info(struct fs_ops * fs,const char * dev,const char * path,void * data)63 add_mnt_info(struct fs_ops *fs, const char *dev, const char *path, void *data)
64 {
65 mnt_info_t *mnt;
66
67 mnt = malloc(sizeof(*mnt));
68 if (mnt == NULL)
69 return (ENOMEM);
70
71 mnt->mnt_fs = fs;
72 mnt->mnt_dev = strdup(dev);
73 mnt->mnt_path = strdup(path);
74 mnt->mnt_data = data;
75 mnt->mnt_refcount = 1;
76
77 if (mnt->mnt_dev == NULL || mnt->mnt_path == NULL) {
78 free_mnt(mnt);
79 return (ENOMEM);
80 }
81 STAILQ_INSERT_TAIL(&mnt_list, mnt, mnt_link);
82 return (0);
83 }
84
85 static void
delete_mnt_info(mnt_info_t * mnt)86 delete_mnt_info(mnt_info_t *mnt)
87 {
88 STAILQ_REMOVE(&mnt_list, mnt, mnt_info, mnt_link);
89 free_mnt(mnt);
90 }
91
92 int
mount(const char * dev,const char * path,int flags __unused,void * data)93 mount(const char *dev, const char *path, int flags __unused, void *data)
94 {
95 mnt_info_t *mnt;
96 int rc = -1;
97
98 /* Is it already mounted? */
99 STAILQ_FOREACH(mnt, &mnt_list, mnt_link) {
100 if (strcmp(dev, mnt->mnt_dev) == 0 &&
101 strcmp(path, mnt->mnt_path) == 0) {
102 mnt->mnt_refcount++;
103 return (0);
104 }
105 }
106
107 for (int i = 0; file_system[i] != NULL; i++) {
108 struct fs_ops *fs;
109
110 fs = file_system[i];
111 if (fs->fo_mount == NULL)
112 continue;
113
114 if (fs->fo_mount(dev, path, &data) != 0)
115 continue;
116
117 rc = add_mnt_info(fs, dev, path, data);
118 if (rc != 0 && mnt->mnt_fs->fo_unmount != NULL) {
119 printf("failed to mount %s: %s\n", dev,
120 strerror(rc));
121 (void)mnt->mnt_fs->fo_unmount(dev, data);
122 }
123 break;
124 }
125
126
127 /*
128 * if rc is -1, it means we have no file system with fo_mount()
129 * callback, or all fo_mount() calls failed. As long as we
130 * have missing fo_mount() callbacks, we allow mount() to return 0.
131 */
132 if (rc == -1)
133 rc = 0;
134
135 return (rc);
136 }
137
138 int
unmount(const char * dev,int flags __unused)139 unmount(const char *dev, int flags __unused)
140 {
141 mnt_info_t *mnt;
142 int rv;
143
144 rv = 0;
145 STAILQ_FOREACH(mnt, &mnt_list, mnt_link) {
146 if (strcmp(dev, mnt->mnt_dev) == 0) {
147 if (mnt->mnt_refcount > 1) {
148 mnt->mnt_refcount--;
149 break;
150 }
151
152 if (mnt->mnt_fs->fo_unmount != NULL)
153 rv = mnt->mnt_fs->fo_unmount(dev,
154 mnt->mnt_data);
155 delete_mnt_info(mnt);
156 break;
157 }
158 }
159
160 if (rv != 0)
161 printf("failed to unmount %s: %d\n", dev, rv);
162 return (0);
163 }
164