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本帖最后由 T-Bagwell 于 2010-08-14 11:30 编辑
小弟是个菜鸟，如果写得有错误的地方，请不吝赐教
kernel version: 2.6.35
从ext4文件的init开始分析一下，暂时先不去看cache的使用- register_as_ext2();
- register_as_ext3();
- err = register_filesystem(&ext4_fs_type);
看一下注册的过程- 56 /**
- 57 * register_filesystem - register a new filesystem
- 58 * @fs: the file system structure
- 59 *
- 60 * Adds the file system passed to the list of file systems the kernel
- 61 * is aware of for mount and other syscalls. Returns 0 on success,
- 62 * or a negative errno code on an error.
- 63 *
- 64 * The &struct file_system_type that is passed is linked into the kernel
- 65 * structures and must not be freed until the file system has been
- 66 * unregistered.
- 67 */
- 68
- 69 int register_filesystem(struct file_system_type * fs)
- 70 {
- 71 int res = 0;
- 72 struct file_system_type ** p;
- 73
- 74 BUG_ON(strchr(fs->name, '.'));
- 75 if (fs->next)
- 76 return -EBUSY;
- 77 INIT_LIST_HEAD(&fs->fs_supers);
- 78 write_lock(&file_systems_lock);
- 79 p = find_filesystem(fs->name, strlen(fs->name));
- 80 if (*p)
- 81 res = -EBUSY;
- 82 else
- 83 *p = fs;
- 84 write_unlock(&file_systems_lock);
- 85 return res;
- 86 }
- 87
- 88 EXPORT_SYMBOL(register_filesystem);
注册的ext4的文件系统的类型结构，这个在do_kernel_mount的时候会通过这个的name来查找fstype- static struct file_system_type ext4_fs_type = {
- .owner = THIS_MODULE,
- .name = "ext4",
- .get_sb = ext4_get_sb,
- .kill_sb = kill_block_super,
- .fs_flags = FS_REQUIRES_DEV,
- };
- 2122 SYSCALL_DEFINE5(mount, char __user *, dev_name, char __user *, dir_name,
- 2123 char __user *, type, unsigned long, flags, void __user *, data)
- 2124 {
- 2125 int ret;
- 2126 char *kernel_type;
- 2127 char *kernel_dir;
- 2128 char *kernel_dev;
- 2129 unsigned long data_page;
- 2130
- 2131 ret = copy_mount_string(type, &kernel_type);
- 2132 if (ret < 0)
- 2133 goto out_type;
- 2134
- 2135 kernel_dir = getname(dir_name);
- 2136 if (IS_ERR(kernel_dir)) {
- 2137 ret = PTR_ERR(kernel_dir);
- 2138 goto out_dir;
- 2139 }
- 2140
- 2141 ret = copy_mount_string(dev_name, &kernel_dev);
- 2142 if (ret < 0)
- 2143 goto out_dev;
- 2144
- 2145 ret = copy_mount_options(data, &data_page);
- 2146 if (ret < 0)
- 2147 goto out_data;
- 2148
- 2149 ret = do_mount(kernel_dev, kernel_dir, kernel_type, flags,
- 2150 (void *) data_page);
- 2151
- 2152 free_page(data_page);
- 2153 out_data:
- 2154 kfree(kernel_dev);
- 2155 out_dev:
- 2156 putname(kernel_dir);
- 2157 out_dir:
- 2158 kfree(kernel_type);
- 2159 out_type:
- 2160 return ret;
- 2161 }
- 1942 long do_mount(char *dev_name, char *dir_name, char *type_page,
- 1943 unsigned long flags, void *data_page)
- 1944 {
- 1945 struct path path;
- 1946 int retval = 0;
- 1947 int mnt_flags = 0;
- 1948
- 1949 /* Discard magic */
- 1950 if ((flags & MS_MGC_MSK) == MS_MGC_VAL)
- 1951 flags &= ~MS_MGC_MSK;
- 1952
- 1953 /* Basic sanity checks */
- 1954
- 1955 if (!dir_name || !*dir_name || !memchr(dir_name, 0, PAGE_SIZE))
- 1956 return -EINVAL;
- 1957
- 1958 if (data_page)
- 1959 ((char *)data_page)[PAGE_SIZE - 1] = 0;
- 1960
- 1961 /* ... and get the mountpoint */
- 1962 retval = kern_path(dir_name, LOOKUP_FOLLOW, &path);
- 1963 if (retval)
- 1964 return retval;
- 1965
- 1966 retval = security_sb_mount(dev_name, &path,
- 1967 type_page, flags, data_page);
- 1968 if (retval)
- 1969 goto dput_out;
- 1970
- 1971 /* Default to relatime unless overriden */
- 1972 if (!(flags & MS_NOATIME))
- 1973 mnt_flags |= MNT_RELATIME;
- 1974
- 1975 /* Separate the per-mountpoint flags */
- 1976 if (flags & MS_NOSUID)
- 1977 mnt_flags |= MNT_NOSUID;
- 1978 if (flags & MS_NODEV)
- 1979 mnt_flags |= MNT_NODEV;
- 1980 if (flags & MS_NOEXEC)
- 1981 mnt_flags |= MNT_NOEXEC;
- 1982 if (flags & MS_NOATIME)
- 1983 mnt_flags |= MNT_NOATIME;
- 1984 if (flags & MS_NODIRATIME)
- 1985 mnt_flags |= MNT_NODIRATIME;
- 1986 if (flags & MS_STRICTATIME)
- 1987 mnt_flags &= ~(MNT_RELATIME | MNT_NOATIME);
- 1988 if (flags & MS_RDONLY)
- 1989 mnt_flags |= MNT_READONLY;
- 1990
- 1991 flags &= ~(MS_NOSUID | MS_NOEXEC | MS_NODEV | MS_ACTIVE | MS_BORN |
- 1992 MS_NOATIME | MS_NODIRATIME | MS_RELATIME| MS_KERNMOUNT |
- 1993 MS_STRICTATIME);
- 1994
- 1995 if (flags & MS_REMOUNT)
- 1996 retval = do_remount(&path, flags & ~MS_REMOUNT, mnt_flags,
- 1997 data_page);
- 1998 else if (flags & MS_BIND)
- 1999 retval = do_loopback(&path, dev_name, flags & MS_REC);
- 2000 else if (flags & (MS_SHARED | MS_PRIVATE | MS_SLAVE | MS_UNBINDABLE))
- 2001 retval = do_change_type(&path, flags);
- 2002 else if (flags & MS_MOVE)
- 2003 retval = do_move_mount(&path, dev_name);
- 2004 else
- 2005 retval = do_new_mount(&path, type_page, flags, mnt_flags,
- 2006 dev_name, data_page);
- 2007 dput_out:
- 2008 path_put(&path);
- 2009 return retval;
- 2010 }
然后通过传递的flag来判断挂载操作， 这些flag可以在man 2 mount中看到说明，这个与mount命令有区别，mount命令要在应用程序里面做很多- [root@T-bagwell ~]# strace mount -t ext4 /dev/sdc1 /mnt
- execve("/bin/mount", ["mount", "-t", "ext4", "/dev/sdc1", "/mnt"], [/* 26 vars */]) = 0
- brk(0) = 0xb894c000
- mmap2(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0xb777a000
- access("/etc/ld.so.preload", R_OK) = -1 ENOENT (No such file or directory)
- open("/etc/ld.so.cache", O_RDONLY) = 3
- fstat64(3, {st_mode=S_IFREG|0644, st_size=59157, ...}) = 0
- mmap2(NULL, 59157, PROT_READ, MAP_PRIVATE, 3, 0) = 0xb776b000
- close(3) = 0
- open("/lib/libblkid.so.1", O_RDONLY) = 3
- read(3, "\177ELF\1\1\1\0\0\0\0\0\0\0\0\0\3\0\3\0\1\0\0\0\20d\33\0004\0\0\0"..., 512) = 512
- fstat64(3, {st_mode=S_IFREG|0755, st_size=85520, ...}) = 0
- mmap2(NULL, 86652, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0xb7755000
- mmap2(0xb7769000, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x13) = 0xb7769000
- close(3) = 0
- open("/lib/libuuid.so.1", O_RDONLY) = 3
- read(3, "\177ELF\1\1\1\0\0\0\0\0\0\0\0\0\3\0\3\0\1\0\0\0`N\337\0004\0\0\0"..., 512) = 512
- fstat64(3, {st_mode=S_IFREG|0755, st_size=16112, ...}) = 0
- mmap2(NULL, 17072, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0xb7750000
- mmap2(0xb7754000, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x3) = 0xb7754000
- close(3) = 0
- open("/lib/libselinux.so.1", O_RDONLY) = 3
- read(3, "\177ELF\1\1\1\0\0\0\0\0\0\0\0\0\3\0\3\0\1\0\0\0`\201\262\0004\0\0\0"..., 512) = 512
- fstat64(3, {st_mode=S_IFREG|0755, st_size=118316, ...}) = 0
- mmap2(NULL, 121848, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0xb7732000
- mmap2(0xb774e000, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x1b) = 0xb774e000
- close(3) = 0
- open("/lib/libsepol.so.1", O_RDONLY) = 3
- read(3, "\177ELF\1\1\1\0\0\0\0\0\0\0\0\0\3\0\3\0\1\0\0\0\340\337\271\0004\0\0\0"..., 512) = 512
- fstat64(3, {st_mode=S_IFREG|0755, st_size=242288, ...}) = 0
- mmap2(NULL, 244992, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0xb76f6000
- mmap2(0xb7731000, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x3a) = 0xb7731000
- close(3) = 0
- open("/lib/libc.so.6", O_RDONLY) = 3
- read(3, "\177ELF\1\1\1\3\0\0\0\0\0\0\0\0\3\0\3\0\1\0\0\0\20M\225\0004\0\0\0"..., 512) = 512
- fstat64(3, {st_mode=S_IFREG|0755, st_size=2402248, ...}) = 0
- mmap2(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0xb76f5000
- mmap2(NULL, 1526120, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0xb7580000
- mprotect(0xb76ee000, 4096, PROT_NONE) = 0
- mmap2(0xb76ef000, 12288, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x16e) = 0xb76ef000
- mmap2(0xb76f2000, 10600, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0xb76f2000
- close(3) = 0
- open("/lib/libdl.so.2", O_RDONLY) = 3
- read(3, "\177ELF\1\1\1\3\0\0\0\0\0\0\0\0\3\0\3\0\1\0\0\0`Z\253\0004\0\0\0"..., 512) = 512
- fstat64(3, {st_mode=S_IFREG|0755, st_size=28364, ...}) = 0
- mmap2(NULL, 16500, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0xb757b000
- mmap2(0xb757e000, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x2) = 0xb757e000
- close(3) = 0
- mmap2(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0xb757a000
- set_thread_area({entry_number:-1 -> 6, base_addr:0xb757a750, limit:1048575, seg_32bit:1, contents:0, read_exec_only:0, limit_in_pages:1, seg_not_present:0, useable:1}) = 0
- mprotect(0xb757e000, 4096, PROT_READ) = 0
- mprotect(0xb76ef000, 8192, PROT_READ) = 0
- mprotect(0xb774e000, 4096, PROT_READ) = 0
- mprotect(0xb779a000, 4096, PROT_READ) = 0
- munmap(0xb776b000, 59157) = 0
- statfs64("/selinux", 84, {f_type="EXT2_SUPER_MAGIC", f_bsize=4096, f_blocks=3466984, f_bfree=1622516, f_bavail=1446401, f_files=881280, f_ffree=686391, f_fsid={1492870975, 1857190837}, f_namelen=255, f_frsize=4096}) = 0
- brk(0) = 0xb894c000
- brk(0xb896d000) = 0xb896d000
- open("/proc/filesystems", O_RDONLY|O_LARGEFILE) = 3
- fstat64(3, {st_mode=S_IFREG|0444, st_size=0, ...}) = 0
- mmap2(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0xb7779000
- read(3, "nodev\tsysfs\nnodev\trootfs\nnodev\tb"..., 1024) = 283
- read(3, "", 1024) = 0
- close(3) = 0
- munmap(0xb7779000, 4096) = 0
- open("/usr/lib/locale/locale-archive", O_RDONLY|O_LARGEFILE) = 3
- fstat64(3, {st_mode=S_IFREG|0644, st_size=98765760, ...}) = 0
- mmap2(NULL, 2097152, PROT_READ, MAP_PRIVATE, 3, 0) = 0xb737a000
- close(3) = 0
- umask(022) = 022
- open("/dev/null", O_RDWR|O_LARGEFILE) = 3
- close(3) = 0
- getuid32() = 0
- geteuid32() = 0
- readlink("/dev", 0xbf909b5b, 4096) = -1 EINVAL (Invalid argument)
- readlink("/dev/sdc1", 0xbf909b5b, 4096) = -1 EINVAL (Invalid argument)
- stat64("/sbin/mount.ext4", 0xbf90a8f8) = -1 ENOENT (No such file or directory)
- rt_sigprocmask(SIG_BLOCK, ~[TRAP SEGV RTMIN RT_1], NULL, 8) = 0
- stat64("/sbin/mount.ext4", 0xbf90a8b8) = -1 ENOENT (No such file or directory)
- [color=Red]*********************************关键是这里****************************************
- mount("/dev/sdc1", "/mnt", "ext4", MS_MGC_VAL, NULL) = 0[/color]
- readlink("/dev", 0xbf90995b, 4096) = -1 EINVAL (Invalid argument)
- readlink("/dev/sdc1", 0xbf90995b, 4096) = -1 EINVAL (Invalid argument)
- readlink("/mnt", 0xbf90995b, 4096) = -1 EINVAL (Invalid argument)
- lstat64("/etc/mtab", {st_mode=S_IFREG|0644, st_size=279, ...}) = 0
- open("/etc/mtab", O_RDWR|O_CREAT|O_LARGEFILE, 0644) = 3
- close(3) = 0
- rt_sigaction(SIGHUP, {0xb77a3a90, ~[RTMIN RT_1], 0}, NULL, 8) = 0
- rt_sigaction(SIGINT, {0xb77a3a90, ~[RTMIN RT_1], 0}, NULL, 8) = 0
- rt_sigaction(SIGQUIT, {0xb77a3a90, ~[RTMIN RT_1], 0}, NULL, 8) = 0
- rt_sigaction(SIGILL, {0xb77a3a90, ~[RTMIN RT_1], 0}, NULL, 8) = 0
- rt_sigaction(SIGTRAP, {0xb77a3a90, ~[RTMIN RT_1], 0}, NULL, 8) = 0
- rt_sigaction(SIGABRT, {0xb77a3a90, ~[RTMIN RT_1], 0}, NULL, 8) = 0
- rt_sigaction(SIGBUS, {0xb77a3a90, ~[RTMIN RT_1], 0}, NULL, 8) = 0
- rt_sigaction(SIGFPE, {0xb77a3a90, ~[RTMIN RT_1], 0}, NULL, 8) = 0
- rt_sigaction(SIGKILL, {0xb77a3a90, ~[RTMIN RT_1], 0}, NULL, 8) = -1 EINVAL (Invalid argument)
- rt_sigaction(SIGUSR1, {0xb77a3a90, ~[RTMIN RT_1], 0}, NULL, 8) = 0
- rt_sigaction(SIGSEGV, {0xb77a3a90, ~[RTMIN RT_1], 0}, NULL, 8) = 0
- rt_sigaction(SIGUSR2, {0xb77a3a90, ~[RTMIN RT_1], 0}, NULL, 8) = 0
- rt_sigaction(SIGPIPE, {0xb77a3a90, ~[RTMIN RT_1], 0}, NULL, 8) = 0
- rt_sigaction(SIGALRM, {0xb77a2eb0, ~[RTMIN RT_1], 0}, NULL, 8) = 0
- rt_sigaction(SIGTERM, {0xb77a3a90, ~[RTMIN RT_1], 0}, NULL, 8) = 0
- rt_sigaction(SIGSTKFLT, {0xb77a3a90, ~[RTMIN RT_1], 0}, NULL, 8) = 0
- getpid() = 1406
- open("/etc/mtab~1406", O_WRONLY|O_CREAT|O_LARGEFILE, 0600) = 3
- close(3) = 0
- gettimeofday({1281688440, 625200}, NULL) = 0
- link("/etc/mtab~1406", "/etc/mtab~") = 0
- open("/etc/mtab~", O_WRONLY|O_LARGEFILE) = 3
- fcntl64(3, F_SETLK64, {type=F_WRLCK, whence=SEEK_SET, start=0, len=0}, 0xbf90a92c) = 0
- unlink("/etc/mtab~1406") = 0
- umask(077) = 022
- open("/etc/mtab", O_RDWR|O_CREAT|O_APPEND|O_LARGEFILE, 0666) = 4
- umask(022) = 077
- fstat64(4, {st_mode=S_IFREG|0644, st_size=279, ...}) = 0
- mmap2(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0xb7779000
- fstat64(4, {st_mode=S_IFREG|0644, st_size=279, ...}) = 0
- _llseek(4, 0, [0], SEEK_SET) = 0
- read(4, "/dev/sda1 / ext4 rw 0 0\nproc /pr"..., 279) = 279
- write(4, "/dev/sdc1 /mnt ext4 rw 0 0\n", 27) = 27
- close(4) = 0
- munmap(0xb7779000, 4096) = 0
- close(3) = 0
- unlink("/etc/mtab~") = 0
- rt_sigprocmask(SIG_UNBLOCK, ~[TRAP SEGV RTMIN RT_1], NULL, 8) = 0
- exit_group(0) = ?
- [root@T-bagwell ~]# strace mount -t ext4 -o remount /dev/sdc1 /mnt
- execve("/bin/mount", ["mount", "-t", "ext4", "-o", "remount", "/dev/sdc1", "/mnt"], [/* 26 vars */]) = 0
- brk(0) = 0xb7dee000
- mmap2(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0xb7730000
- access("/etc/ld.so.preload", R_OK) = -1 ENOENT (No such file or directory)
- open("/etc/ld.so.cache", O_RDONLY) = 3
- fstat64(3, {st_mode=S_IFREG|0644, st_size=59157, ...}) = 0
- mmap2(NULL, 59157, PROT_READ, MAP_PRIVATE, 3, 0) = 0xb7721000
- close(3) = 0
- open("/lib/libblkid.so.1", O_RDONLY) = 3
- read(3, "\177ELF\1\1\1\0\0\0\0\0\0\0\0\0\3\0\3\0\1\0\0\0\20d\33\0004\0\0\0"..., 512) = 512
- fstat64(3, {st_mode=S_IFREG|0755, st_size=85520, ...}) = 0
- mmap2(NULL, 86652, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0xb770b000
- mmap2(0xb771f000, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x13) = 0xb771f000
- close(3) = 0
- open("/lib/libuuid.so.1", O_RDONLY) = 3
- read(3, "\177ELF\1\1\1\0\0\0\0\0\0\0\0\0\3\0\3\0\1\0\0\0`N\337\0004\0\0\0"..., 512) = 512
- fstat64(3, {st_mode=S_IFREG|0755, st_size=16112, ...}) = 0
- mmap2(NULL, 17072, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0xb7706000
- mmap2(0xb770a000, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x3) = 0xb770a000
- close(3) = 0
- open("/lib/libselinux.so.1", O_RDONLY) = 3
- read(3, "\177ELF\1\1\1\0\0\0\0\0\0\0\0\0\3\0\3\0\1\0\0\0`\201\262\0004\0\0\0"..., 512) = 512
- fstat64(3, {st_mode=S_IFREG|0755, st_size=118316, ...}) = 0
- mmap2(NULL, 121848, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0xb76e8000
- mmap2(0xb7704000, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x1b) = 0xb7704000
- close(3) = 0
- open("/lib/libsepol.so.1", O_RDONLY) = 3
- read(3, "\177ELF\1\1\1\0\0\0\0\0\0\0\0\0\3\0\3\0\1\0\0\0\340\337\271\0004\0\0\0"..., 512) = 512
- fstat64(3, {st_mode=S_IFREG|0755, st_size=242288, ...}) = 0
- mmap2(NULL, 244992, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0xb76ac000
- mmap2(0xb76e7000, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x3a) = 0xb76e7000
- close(3) = 0
- open("/lib/libc.so.6", O_RDONLY) = 3
- read(3, "\177ELF\1\1\1\3\0\0\0\0\0\0\0\0\3\0\3\0\1\0\0\0\20M\225\0004\0\0\0"..., 512) = 512
- fstat64(3, {st_mode=S_IFREG|0755, st_size=2402248, ...}) = 0
- mmap2(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0xb76ab000
- mmap2(NULL, 1526120, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0xb7536000
- mprotect(0xb76a4000, 4096, PROT_NONE) = 0
- mmap2(0xb76a5000, 12288, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x16e) = 0xb76a5000
- mmap2(0xb76a8000, 10600, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0xb76a8000
- close(3) = 0
- open("/lib/libdl.so.2", O_RDONLY) = 3
- read(3, "\177ELF\1\1\1\3\0\0\0\0\0\0\0\0\3\0\3\0\1\0\0\0`Z\253\0004\0\0\0"..., 512) = 512
- fstat64(3, {st_mode=S_IFREG|0755, st_size=28364, ...}) = 0
- mmap2(NULL, 16500, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0xb7531000
- mmap2(0xb7534000, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x2) = 0xb7534000
- close(3) = 0
- mmap2(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0xb7530000
- set_thread_area({entry_number:-1 -> 6, base_addr:0xb7530750, limit:1048575, seg_32bit:1, contents:0, read_exec_only:0, limit_in_pages:1, seg_not_present:0, useable:1}) = 0
- mprotect(0xb7534000, 4096, PROT_READ) = 0
- mprotect(0xb76a5000, 8192, PROT_READ) = 0
- mprotect(0xb7704000, 4096, PROT_READ) = 0
- mprotect(0xb7750000, 4096, PROT_READ) = 0
- munmap(0xb7721000, 59157) = 0
- statfs64("/selinux", 84, {f_type="EXT2_SUPER_MAGIC", f_bsize=4096, f_blocks=3466984, f_bfree=1622515, f_bavail=1446400, f_files=881280, f_ffree=686391, f_fsid={1492870975, 1857190837}, f_namelen=255, f_frsize=4096}) = 0
- brk(0) = 0xb7dee000
- brk(0xb7e0f000) = 0xb7e0f000
- open("/proc/filesystems", O_RDONLY|O_LARGEFILE) = 3
- fstat64(3, {st_mode=S_IFREG|0444, st_size=0, ...}) = 0
- mmap2(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0xb772f000
- read(3, "nodev\tsysfs\nnodev\trootfs\nnodev\tb"..., 1024) = 283
- read(3, "", 1024) = 0
- close(3) = 0
- munmap(0xb772f000, 4096) = 0
- open("/usr/lib/locale/locale-archive", O_RDONLY|O_LARGEFILE) = 3
- fstat64(3, {st_mode=S_IFREG|0644, st_size=98765760, ...}) = 0
- mmap2(NULL, 2097152, PROT_READ, MAP_PRIVATE, 3, 0) = 0xb7330000
- close(3) = 0
- umask(022) = 022
- open("/dev/null", O_RDWR|O_LARGEFILE) = 3
- close(3) = 0
- getuid32() = 0
- geteuid32() = 0
- readlink("/dev", 0xbf9fc3ab, 4096) = -1 EINVAL (Invalid argument)
- readlink("/dev/sdc1", 0xbf9fc3ab, 4096) = -1 EINVAL (Invalid argument)
- stat64("/sbin/mount.ext4", 0xbf9fd148) = -1 ENOENT (No such file or directory)
- rt_sigprocmask(SIG_BLOCK, ~[TRAP SEGV RTMIN RT_1], NULL, 8) = 0
- stat64("/sbin/mount.ext4", 0xbf9fd108) = -1 ENOENT (No such file or directory)
- [color=Red]*********************************关键是这里**********因为是-o remount，所以这里多了一个MS_REMOUNT******************************
- mount("/dev/sdc1", "/mnt", 0xb7def0d8, MS_MGC_VAL|MS_REMOUNT, NULL) = 0[/color]
- readlink("/dev", 0xbf9fc1ab, 4096) = -1 EINVAL (Invalid argument)
- readlink("/dev/sdc1", 0xbf9fc1ab, 4096) = -1 EINVAL (Invalid argument)
- readlink("/mnt", 0xbf9fc1ab, 4096) = -1 EINVAL (Invalid argument)
- lstat64("/etc/mtab", {st_mode=S_IFREG|0644, st_size=306, ...}) = 0
- open("/etc/mtab", O_RDWR|O_CREAT|O_LARGEFILE, 0644) = 3
- close(3) = 0
- open("/etc/mtab", O_RDWR|O_CREAT|O_LARGEFILE, 0644) = 3
- close(3) = 0
- rt_sigaction(SIGHUP, {0xb7759a90, ~[RTMIN RT_1], 0}, NULL, 8) = 0
- rt_sigaction(SIGINT, {0xb7759a90, ~[RTMIN RT_1], 0}, NULL, 8) = 0
- rt_sigaction(SIGQUIT, {0xb7759a90, ~[RTMIN RT_1], 0}, NULL, 8) = 0
- rt_sigaction(SIGILL, {0xb7759a90, ~[RTMIN RT_1], 0}, NULL, 8) = 0
- rt_sigaction(SIGTRAP, {0xb7759a90, ~[RTMIN RT_1], 0}, NULL, 8) = 0
- rt_sigaction(SIGABRT, {0xb7759a90, ~[RTMIN RT_1], 0}, NULL, 8) = 0
- rt_sigaction(SIGBUS, {0xb7759a90, ~[RTMIN RT_1], 0}, NULL, 8) = 0
- rt_sigaction(SIGFPE, {0xb7759a90, ~[RTMIN RT_1], 0}, NULL, 8) = 0
- rt_sigaction(SIGKILL, {0xb7759a90, ~[RTMIN RT_1], 0}, NULL, 8) = -1 EINVAL (Invalid argument)
- rt_sigaction(SIGUSR1, {0xb7759a90, ~[RTMIN RT_1], 0}, NULL, 8) = 0
- rt_sigaction(SIGSEGV, {0xb7759a90, ~[RTMIN RT_1], 0}, NULL, 8) = 0
- rt_sigaction(SIGUSR2, {0xb7759a90, ~[RTMIN RT_1], 0}, NULL, 8) = 0
- rt_sigaction(SIGPIPE, {0xb7759a90, ~[RTMIN RT_1], 0}, NULL, 8) = 0
- rt_sigaction(SIGALRM, {0xb7758eb0, ~[RTMIN RT_1], 0}, NULL, 8) = 0
- rt_sigaction(SIGTERM, {0xb7759a90, ~[RTMIN RT_1], 0}, NULL, 8) = 0
- rt_sigaction(SIGSTKFLT, {0xb7759a90, ~[RTMIN RT_1], 0}, NULL, 8) = 0
- getpid() = 1415
- open("/etc/mtab~1415", O_WRONLY|O_CREAT|O_LARGEFILE, 0600) = 3
- close(3) = 0
- gettimeofday({1281688501, 78710}, NULL) = 0
- link("/etc/mtab~1415", "/etc/mtab~") = 0
- open("/etc/mtab~", O_WRONLY|O_LARGEFILE) = 3
- fcntl64(3, F_SETLK64, {type=F_WRLCK, whence=SEEK_SET, start=0, len=0}, 0xbf9fd08c) = 0
- unlink("/etc/mtab~1415") = 0
- umask(077) = 022
- open("/etc/mtab", O_RDONLY|O_LARGEFILE) = 4
- umask(022) = 077
- fstat64(4, {st_mode=S_IFREG|0644, st_size=306, ...}) = 0
- mmap2(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0xb772f000
- read(4, "/dev/sda1 / ext4 rw 0 0\nproc /pr"..., 4096) = 306
- read(4, "", 4096) = 0
- close(4) = 0
- munmap(0xb772f000, 4096) = 0
- umask(077) = 022
- open("/etc/mtab.tmp", O_WRONLY|O_CREAT|O_TRUNC|O_LARGEFILE, 0666) = 4
- umask(022) = 077
- fstat64(4, {st_mode=S_IFREG|0600, st_size=0, ...}) = 0
- mmap2(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0xb772f000
- fstat64(4, {st_mode=S_IFREG|0600, st_size=0, ...}) = 0
- _llseek(4, 0, [0], SEEK_SET) = 0
- write(4, "/dev/sda1 / ext4 rw 0 0\n", 24) = 24
- fstat64(4, {st_mode=S_IFREG|0600, st_size=24, ...}) = 0
- _llseek(4, 24, [24], SEEK_SET) = 0
- write(4, "proc /proc proc rw 0 0\n", 23) = 23
- fstat64(4, {st_mode=S_IFREG|0600, st_size=47, ...}) = 0
- _llseek(4, 47, [47], SEEK_SET) = 0
- write(4, "sysfs /sys sysfs rw 0 0\n", 24) = 24
- fstat64(4, {st_mode=S_IFREG|0600, st_size=71, ...}) = 0
- _llseek(4, 71, [71], SEEK_SET) = 0
- write(4, "devpts /dev/pts devpts rw,gid=5,"..., 45) = 45
- fstat64(4, {st_mode=S_IFREG|0600, st_size=116, ...}) = 0
- _llseek(4, 116, [116], SEEK_SET) = 0
- write(4, "tmpfs /dev/shm tmpfs rw 0 0\n", 28) = 28
- fstat64(4, {st_mode=S_IFREG|0600, st_size=144, ...}) = 0
- _llseek(4, 144, [144], SEEK_SET) = 0
- write(4, "none /proc/sys/fs/binfmt_misc bi"..., 49) = 49
- fstat64(4, {st_mode=S_IFREG|0600, st_size=193, ...}) = 0
- _llseek(4, 193, [193], SEEK_SET) = 0
- write(4, "sunrpc /var/lib/nfs/rpc_pipefs r"..., 49) = 49
- fstat64(4, {st_mode=S_IFREG|0600, st_size=242, ...}) = 0
- _llseek(4, 242, [242], SEEK_SET) = 0
- write(4, "/dev/sdb1 /media/android ext4 rw"..., 37) = 37
- fstat64(4, {st_mode=S_IFREG|0600, st_size=279, ...}) = 0
- _llseek(4, 279, [279], SEEK_SET) = 0
- fchmod(4, 0644) = 0
- stat64("/etc/mtab", {st_mode=S_IFREG|0644, st_size=306, ...}) = 0
- fchown32(4, 0, 0) = 0
- write(4, "/dev/sdc1 /mnt ext4 rw 0 0\n", 27) = 27
- close(4) = 0
- munmap(0xb772f000, 4096) = 0
- rename("/etc/mtab.tmp", "/etc/mtab") = 0
- close(3) = 0
- unlink("/etc/mtab~") = 0
- rt_sigprocmask(SIG_UNBLOCK, ~[TRAP SEGV RTMIN RT_1], NULL, 8) = 0
- exit_group(0)
- 1669 /*
- 1670 * create a new mount for userspace and request it to be added into the
- 1671 * namespace's tree
- 1672 */
- 1673 static int do_new_mount(struct path *path, char *type, int flags,
- 1674 int mnt_flags, char *name, void *data)
- 1675 {
- 1676 struct vfsmount *mnt;
- 1677
- 1678 if (!type)
- 1679 return -EINVAL;
- 1680
- 1681 /* we need capabilities... */
- 1682 if (!capable(CAP_SYS_ADMIN))
- 1683 return -EPERM;
- 1684
- 1685 lock_kernel();
- 1686 mnt = do_kern_mount(type, flags, name, data);
- 1687 unlock_kernel();
- 1688 if (IS_ERR(mnt))
- 1689 return PTR_ERR(mnt);
- 1690
- 1691 return do_add_mount(mnt, path, mnt_flags, NULL);
- 1692 }
先看do_kernel_mount- 1079 struct vfsmount *
- 1080 do_kern_mount(const char *fstype, int flags, const char *name, void *data)
- 1081 {
- 1082 struct file_system_type *type = get_fs_type(fstype);
- 1083 struct vfsmount *mnt;
- 1084 if (!type)
- 1085 return ERR_PTR(-ENODEV);
- 1086 mnt = vfs_kern_mount(type, flags, name, data);
- 1087 if (!IS_ERR(mnt) && (type->fs_flags & FS_HAS_SUBTYPE) &&
- 1088 !mnt->mnt_sb->s_subtype)
- 1089 mnt = fs_set_subtype(mnt, fstype);
- 1090 put_filesystem(type);
- 1091 return mnt;
- 1092 }
- 1093 EXPORT_SYMBOL_GPL(do_kern_mount);
进入到vfs_kern_mount里面看一下，里面肯定会调到get_sb,- 899 struct vfsmount *
- 900 vfs_kern_mount(struct file_system_type *type, int flags, const char *name, void *data)
- 901 {
- 902 struct vfsmount *mnt;
- 903 char *secdata = NULL;
- 904 int error;
- 905
- 906 if (!type)
- 907 return ERR_PTR(-ENODEV);
- 908
- 909 error = -ENOMEM;
- 910 mnt = alloc_vfsmnt(name);
- 911 if (!mnt)
- 912 goto out;
- 913
- 914 if (flags & MS_KERNMOUNT)
- 915 mnt->mnt_flags = MNT_INTERNAL;
- 916
- 917 if (data && !(type->fs_flags & FS_BINARY_MOUNTDATA)) {
- 918 secdata = alloc_secdata();
- 919 if (!secdata)
- 920 goto out_mnt;
- 921
- 922 error = security_sb_copy_data(data, secdata);
- 923 if (error)
- 924 goto out_free_secdata;
- 925 }
- 926*************************在这呢，这里的get_sb就是fs/ext4/super.c里面的ext4_get_sb***********************************
- 927 error = type->get_sb(type, flags, name, data, mnt);
- 928 if (error < 0)
- 929 goto out_free_secdata;
- 930 BUG_ON(!mnt->mnt_sb);
- 931 WARN_ON(!mnt->mnt_sb->s_bdi);
- 932 mnt->mnt_sb->s_flags |= MS_BORN;
- 933
- 934 error = security_sb_kern_mount(mnt->mnt_sb, flags, secdata);
- 935 if (error)
- 936 goto out_sb;
- 937
- 938 /*
- 939 * filesystems should never set s_maxbytes larger than MAX_LFS_FILESIZE
- 940 * but s_maxbytes was an unsigned long long for many releases. Throw
- 941 * this warning for a little while to try and catch filesystems that
- 942 * violate this rule. This warning should be either removed or
- 943 * converted to a BUG() in 2.6.34.
- 944 */
- 945 WARN((mnt->mnt_sb->s_maxbytes < 0), "%s set sb->s_maxbytes to "
- 946 "negative value (%lld)\n", type->name, mnt->mnt_sb->s_maxbytes);
- 947
- 948 mnt->mnt_mountpoint = mnt->mnt_root;
- 949 mnt->mnt_parent = mnt;
- 950 up_write(&mnt->mnt_sb->s_umount);
- 951 free_secdata(secdata);
- 952 return mnt;
- 953 out_sb:
- 954 dput(mnt->mnt_root);
- 955 deactivate_locked_super(mnt->mnt_sb);
- 956 out_free_secdata:
- 957 free_secdata(secdata);
- 958 out_mnt:
- 959 free_vfsmnt(mnt);
- 960 out:
- 961 return ERR_PTR(error);
- 962 }
- 963
- 964 EXPORT_SYMBOL_GPL(vfs_kern_mount);
- 4232 static int ext4_get_sb(struct file_system_type *fs_type, int flags,
- 4233 const char *dev_name, void *data, struct vfsmount *mnt)
- 4234 {
- 4235 return get_sb_bdev(fs_type, flags, dev_name, data, ext4_fill_super,mnt);
- 4236 }
get_sb_bdev里面会用到ext4_fill_super，因为要注册一下里面的细节，比如创建节点，文件，目录，链接，读文件，读目录，写文件，写目录，删除文件，很多很多。
后面涉及到了对块设备操作的很多工作，文件系统最关键的就是管理文件，并且是块设备上的，这个块设备就是在get_sb_bdev里面得到的- 747 int get_sb_bdev(struct file_system_type *fs_type,
- 748 int flags, const char *dev_name, void *data,
- 749 int (*fill_super)(struct super_block *, void *, int),
- 750 struct vfsmount *mnt)
- 751 {
- 752 struct block_device *bdev;
- 753 struct super_block *s;
- 754 fmode_t mode = FMODE_READ;
- 755 int error = 0;
- 756
- 757 if (!(flags & MS_RDONLY))
- 758 mode |= FMODE_WRITE;
- 759
- 760 bdev = open_bdev_exclusive(dev_name, mode, fs_type);
- 761 if (IS_ERR(bdev))
- 762 return PTR_ERR(bdev);
- ……
- 799
- 800 s->s_flags = flags;
- 801 s->s_mode = mode;
- 802 strlcpy(s->s_id, bdevname(bdev, b), sizeof(s->s_id));
- 803 sb_set_blocksize(s, block_size(bdev));
- 804 error = fill_super(s, data, flags & MS_SILENT ? 1 : 0);
- 805 if (error) {
- 806 deactivate_locked_super(s);
- 807 goto error;
- 808 }
- 809
- 810 s->s_flags |= MS_ACTIVE;
- 811 bdev->bd_super = s;
- 812 }
- 813
- 814 simple_set_mnt(mnt, s);
- 815 return 0;
- ……
就这样，对磁盘文件操作就了解了
通过这个fill_super来进行读读块设备- 2545 static int ext4_fill_super(struct super_block *sb, void *data, int silent)
- 2546 __releases(kernel_lock)
- 2547 __acquires(kernel_lock)
- 2548 {
- 2549 char *orig_data = kstrdup(data, GFP_KERNEL);
- 2550 struct buffer_head *bh;
- 2551 struct ext4_super_block *es = NULL;
- 2552 struct ext4_sb_info *sbi;
- 2553 ext4_fsblk_t block;
- 2554 ext4_fsblk_t sb_block = get_sb_block(&data);
- 2555 ext4_fsblk_t logical_sb_block;
- 2556 unsigned long offset = 0;
- ……
- 2580 }
- 2581 sb->s_fs_info = sbi;
- 2582 sbi->s_mount_opt = 0;
- 2583 sbi->s_resuid = EXT4_DEF_RESUID;
- 2584 sbi->s_resgid = EXT4_DEF_RESGID;
- 2585 sbi->s_inode_readahead_blks = EXT4_DEF_INODE_READAHEAD_BLKS;
- 2586 sbi->s_sb_block = sb_block;
- 2587 if (sb->s_bdev->bd_part)
- 2588 sbi->s_sectors_written_start =
- 2589 part_stat_read(sb->s_bdev->bd_part, sectors[1]);
- 2590
- 2591 unlock_kernel();
- 2592
- 2593 /* Cleanup superblock name */
- 2594 for (cp = sb->s_id; (cp = strchr(cp, '/'));)
- 2595 *cp = '!';
- 2596
- 2597 ret = -EINVAL;
- 2598 blocksize = sb_min_blocksize(sb, EXT4_MIN_BLOCK_SIZE);
- 2599 if (!blocksize) {
- 2600 ext4_msg(sb, KERN_ERR, "unable to set blocksize");
- 2601 goto out_fail;
- 2602 }
- 2603
- 2604 /*
- 2605 * The ext4 superblock will not be buffer aligned for other than 1kB
- 2606 * block sizes. We need to calculate the offset from buffer start.
- 2607 */
- 2608 if (blocksize != EXT4_MIN_BLOCK_SIZE) {
- 2609 logical_sb_block = sb_block * EXT4_MIN_BLOCK_SIZE;
- 2610 offset = do_div(logical_sb_block, blocksize);
- 2611 } else {
- 2612 logical_sb_block = sb_block;
- 2613 }
- 2614
- 2615 if (!(bh = sb_bread(sb, logical_sb_block))) {
- 2616 ext4_msg(sb, KERN_ERR, "unable to read superblock");
- 2617 goto out_fail;
- 2618 }
- ……
- 2649 if ((def_mount_opts & EXT4_DEFM_JMODE) == EXT4_DEFM_JMODE_DATA)
- 2650 set_opt(sbi->s_mount_opt, JOURNAL_DATA);
- 2651 else if ((def_mount_opts & EXT4_DEFM_JMODE) == EXT4_DEFM_JMODE_ORDERED)
- 2652 set_opt(sbi->s_mount_opt, ORDERED_DATA);
- 2653 else if ((def_mount_opts & EXT4_DEFM_JMODE) == EXT4_DEFM_JMODE_WBACK)
- 2654 set_opt(sbi->s_mount_opt, WRITEBACK_DATA);
- 2655
- 2656 if (le16_to_cpu(sbi->s_es->s_errors) == EXT4_ERRORS_PANIC)
- 2657 set_opt(sbi->s_mount_opt, ERRORS_PANIC);
- 2658 else if (le16_to_cpu(sbi->s_es->s_errors) == EXT4_ERRORS_CONTINUE)
- 2659 set_opt(sbi->s_mount_opt, ERRORS_CONT);
- 2660 else
- 2661 set_opt(sbi->s_mount_opt, ERRORS_RO);
- 2662 if (def_mount_opts & EXT4_DEFM_BLOCK_VALIDITY)
- 2663 set_opt(sbi->s_mount_opt, BLOCK_VALIDITY);
- 2664 if (def_mount_opts & EXT4_DEFM_DISCARD)
- 2665 set_opt(sbi->s_mount_opt, DISCARD);
- ……
- 2931 * set up enough so that it can read an inode
- 2932 */
- 2933 if (!test_opt(sb, NOLOAD) &&
- 2934 EXT4_HAS_COMPAT_FEATURE(sb, EXT4_FEATURE_COMPAT_HAS_JOURNAL))
- 2935 sb->s_op = &ext4_sops;
- 2936 else
- 2937 sb->s_op = &ext4_nojournal_sops;
- 2938 sb->s_export_op = &ext4_export_ops;
- 2939 sb->s_xattr = ext4_xattr_handlers;
- 2940 #ifdef CONFIG_QUOTA
- 2941 sb->s_qcop = &ext4_qctl_operations;
- 2942 sb->dq_op = &ext4_quota_operations;
- 2943 #endif
- ……
- 3052 root = ext4_iget(sb, EXT4_ROOT_INO);
- 3053 if (IS_ERR(root)) {
- 3054 ext4_msg(sb, KERN_ERR, "get root inode failed");
- 3055 ret = PTR_ERR(root);
- 3056 goto failed_mount4;
- 3057 }
- 3058 if (!S_ISDIR(root->i_mode) || !root->i_blocks || !root->i_size) {
- 3059 iput(root);
- 3060 ext4_msg(sb, KERN_ERR, "corrupt root inode, run e2fsck");
- 3061 goto failed_mount4;
- 3062 }
- 3063 sb->s_root = d_alloc_root(root);
- 3064 if (!sb->s_root) {
- 3065 ext4_msg(sb, KERN_ERR, "get root dentry failed");
- 3066 iput(root);
- 3067 ret = -ENOMEM;
- 3068 goto failed_mount4;
- 3069 }
- 3070
- 3071 ext4_setup_super(sb, es, sb->s_flags & MS_RDONLY);
- 3072
然后回到do_new_mount，将挂载点添加到列表里就可以了，这个列表在/proc中可以展现出来- [root@T-bagwell ~]# cat /proc/mounts
- rootfs / rootfs rw 0 0
- /dev/root / ext4 rw,relatime,barrier=1,data=ordered 0 0
- /dev /dev tmpfs rw,relatime,mode=755 0 0
- /proc /proc proc rw,relatime 0 0
- /sys /sys sysfs rw,relatime 0 0
- /proc/bus/usb /proc/bus/usb usbfs rw,relatime 0 0
- devpts /dev/pts devpts rw,relatime,gid=5,mode=620,ptmxmode=000 0 0
- none /proc/sys/fs/binfmt_misc binfmt_misc rw,relatime 0 0
- sunrpc /var/lib/nfs/rpc_pipefs rpc_pipefs rw,relatime 0 0
- /dev/sdb1 /media/android ext4 rw,relatime,barrier=1,data=ordered 0 0
- [root@T-bagwell ~]#
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.png "2015年中国系统架构师大会
日期:2015-06-29 16:11:28")
发表于 2010-08-13 20:38
发表于 2010-08-13 20:50
