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 __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 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 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 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 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 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