1 /*- 2 * Copyright 2021 Toomas Soome <tsoome@me.com> 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 #include <stand.h> 28 #include <sys/queue.h> 29 30 /* 31 * While setting "currdev" environment variable, alse "mount" the 32 * new root file system. This is done to hold disk device open 33 * in between file accesses, and thus preserve block cache for 34 * this device. Additionally, this allows us to optimize filesystem 35 * access by sharing filesystem metadata (like superblock). 36 */ 37 38 typedef STAILQ_HEAD(mnt_info_list, mnt_info) mnt_info_list_t; 39 40 typedef struct mnt_info { 41 STAILQ_ENTRY(mnt_info) mnt_link; /* link in mount list */ 42 const struct fs_ops *mnt_fs; 43 char *mnt_dev; 44 char *mnt_path; 45 unsigned mnt_refcount; 46 void *mnt_data; /* Private state */ 47 } mnt_info_t; 48 49 /* list of mounted filesystems. */ 50 static mnt_info_list_t mnt_list = STAILQ_HEAD_INITIALIZER(mnt_list); 51 52 static void 53 free_mnt(mnt_info_t *mnt) 54 { 55 free(mnt->mnt_dev); 56 free(mnt->mnt_path); 57 free(mnt); 58 } 59 60 static int 61 add_mnt_info(struct fs_ops *fs, const char *dev, const char *path, void *data) 62 { 63 mnt_info_t *mnt; 64 65 mnt = malloc(sizeof(*mnt)); 66 if (mnt == NULL) 67 return (ENOMEM); 68 69 mnt->mnt_fs = fs; 70 mnt->mnt_dev = strdup(dev); 71 mnt->mnt_path = strdup(path); 72 mnt->mnt_data = data; 73 mnt->mnt_refcount = 1; 74 75 if (mnt->mnt_dev == NULL || mnt->mnt_path == NULL) { 76 free_mnt(mnt); 77 return (ENOMEM); 78 } 79 STAILQ_INSERT_TAIL(&mnt_list, mnt, mnt_link); 80 return (0); 81 } 82 83 static void 84 delete_mnt_info(mnt_info_t *mnt) 85 { 86 STAILQ_REMOVE(&mnt_list, mnt, mnt_info, mnt_link); 87 free_mnt(mnt); 88 } 89 90 int 91 mount(const char *dev, const char *path, int flags __unused, void *data) 92 { 93 mnt_info_t *mnt; 94 int rc = -1; 95 96 /* Is it already mounted? */ 97 STAILQ_FOREACH(mnt, &mnt_list, mnt_link) { 98 if (strcmp(dev, mnt->mnt_dev) == 0 && 99 strcmp(path, mnt->mnt_path) == 0) { 100 mnt->mnt_refcount++; 101 return (0); 102 } 103 } 104 105 for (int i = 0; file_system[i] != NULL; i++) { 106 struct fs_ops *fs; 107 108 fs = file_system[i]; 109 if (fs->fo_mount == NULL) 110 continue; 111 112 if (fs->fo_mount(dev, path, &data) != 0) 113 continue; 114 115 rc = add_mnt_info(fs, dev, path, data); 116 if (rc != 0 && mnt->mnt_fs->fo_unmount != NULL) { 117 printf("failed to mount %s: %s\n", dev, 118 strerror(rc)); 119 (void)mnt->mnt_fs->fo_unmount(dev, data); 120 } 121 break; 122 } 123 124 125 /* 126 * if rc is -1, it means we have no file system with fo_mount() 127 * callback, or all fo_mount() calls failed. As long as we 128 * have missing fo_mount() callbacks, we allow mount() to return 0. 129 */ 130 if (rc == -1) 131 rc = 0; 132 133 return (rc); 134 } 135 136 int 137 unmount(const char *dev, int flags __unused) 138 { 139 mnt_info_t *mnt; 140 int rv; 141 142 rv = 0; 143 STAILQ_FOREACH(mnt, &mnt_list, mnt_link) { 144 if (strcmp(dev, mnt->mnt_dev) == 0) { 145 if (mnt->mnt_refcount > 1) { 146 mnt->mnt_refcount--; 147 break; 148 } 149 150 if (mnt->mnt_fs->fo_unmount != NULL) 151 rv = mnt->mnt_fs->fo_unmount(dev, 152 mnt->mnt_data); 153 delete_mnt_info(mnt); 154 break; 155 } 156 } 157 158 if (rv != 0) 159 printf("failed to unmount %s: %d\n", dev, rv); 160 return (0); 161 } 162