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 <stand.h> 27 #include <sys/queue.h> 28 29 /* 30 * While setting "currdev" environment variable, alse "mount" the 31 * new root file system. This is done to hold disk device open 32 * in between file accesses, and thus preserve block cache for 33 * this device. Additionally, this allows us to optimize filesystem 34 * access by sharing filesystem metadata (like superblock). 35 */ 36 37 typedef STAILQ_HEAD(mnt_info_list, mnt_info) mnt_info_list_t; 38 39 typedef struct mnt_info { 40 STAILQ_ENTRY(mnt_info) mnt_link; /* link in mount list */ 41 const struct fs_ops *mnt_fs; 42 char *mnt_dev; 43 char *mnt_path; 44 unsigned mnt_refcount; 45 void *mnt_data; /* Private state */ 46 } mnt_info_t; 47 48 /* list of mounted filesystems. */ 49 static mnt_info_list_t mnt_list = STAILQ_HEAD_INITIALIZER(mnt_list); 50 51 static void 52 free_mnt(mnt_info_t *mnt) 53 { 54 free(mnt->mnt_dev); 55 free(mnt->mnt_path); 56 free(mnt); 57 } 58 59 static int 60 add_mnt_info(struct fs_ops *fs, const char *dev, const char *path, void *data) 61 { 62 mnt_info_t *mnt; 63 64 mnt = malloc(sizeof(*mnt)); 65 if (mnt == NULL) 66 return (ENOMEM); 67 68 mnt->mnt_fs = fs; 69 mnt->mnt_dev = strdup(dev); 70 mnt->mnt_path = strdup(path); 71 mnt->mnt_data = data; 72 mnt->mnt_refcount = 1; 73 74 if (mnt->mnt_dev == NULL || mnt->mnt_path == NULL) { 75 free_mnt(mnt); 76 return (ENOMEM); 77 } 78 STAILQ_INSERT_TAIL(&mnt_list, mnt, mnt_link); 79 return (0); 80 } 81 82 static void 83 delete_mnt_info(mnt_info_t *mnt) 84 { 85 STAILQ_REMOVE(&mnt_list, mnt, mnt_info, mnt_link); 86 free_mnt(mnt); 87 } 88 89 int 90 mount(const char *dev, const char *path, int flags __unused, void *data) 91 { 92 mnt_info_t *mnt; 93 int rc = -1; 94 95 /* Is it already mounted? */ 96 STAILQ_FOREACH(mnt, &mnt_list, mnt_link) { 97 if (strcmp(dev, mnt->mnt_dev) == 0 && 98 strcmp(path, mnt->mnt_path) == 0) { 99 mnt->mnt_refcount++; 100 return (0); 101 } 102 } 103 104 for (int i = 0; file_system[i] != NULL; i++) { 105 struct fs_ops *fs; 106 107 fs = file_system[i]; 108 if (fs->fo_mount == NULL) 109 continue; 110 111 if (fs->fo_mount(dev, path, &data) != 0) 112 continue; 113 114 rc = add_mnt_info(fs, dev, path, data); 115 if (rc != 0 && mnt->mnt_fs->fo_unmount != NULL) { 116 printf("failed to mount %s: %s\n", dev, 117 strerror(rc)); 118 (void)mnt->mnt_fs->fo_unmount(dev, data); 119 } 120 break; 121 } 122 123 124 /* 125 * if rc is -1, it means we have no file system with fo_mount() 126 * callback, or all fo_mount() calls failed. As long as we 127 * have missing fo_mount() callbacks, we allow mount() to return 0. 128 */ 129 if (rc == -1) 130 rc = 0; 131 132 return (rc); 133 } 134 135 int 136 unmount(const char *dev, int flags __unused) 137 { 138 mnt_info_t *mnt; 139 int rv; 140 141 rv = 0; 142 STAILQ_FOREACH(mnt, &mnt_list, mnt_link) { 143 if (strcmp(dev, mnt->mnt_dev) == 0) { 144 if (mnt->mnt_refcount > 1) { 145 mnt->mnt_refcount--; 146 break; 147 } 148 149 if (mnt->mnt_fs->fo_unmount != NULL) 150 rv = mnt->mnt_fs->fo_unmount(dev, 151 mnt->mnt_data); 152 delete_mnt_info(mnt); 153 break; 154 } 155 } 156 157 if (rv != 0) 158 printf("failed to unmount %s: %d\n", dev, rv); 159 return (0); 160 } 161