Merge "fs_mgr: Support filesystem labels in fstab" (4e0bdd10) · Commits · e / os / android_system_core

fs_mgr/fs_mgr.c

+91 −0

Original line number	Diff line number	Diff line
		@@ -28,6 +28,9 @@
		#include <libgen.h>
		#include <time.h>
		#include <sys/swap.h>
		#include <dirent.h>
		#include <ext4.h>
		#include <ext4_sb.h>

		#include <linux/loop.h>
		#include <private/android_filesystem_config.h>
		@@ -325,6 +328,83 @@ static int mount_with_alternatives(struct fstab fstab, int start_idx, int end_
		return 0;
		}

		static int translate_ext_labels(struct fstab_rec *rec)
		{
		DIR *blockdir = NULL;
		struct dirent *ent;
		char *label;
		size_t label_len;
		int ret = -1;

		if (strncmp(rec->blk_device, "LABEL=", 6))
		return 0;

		label = rec->blk_device + 6;
		label_len = strlen(label);

		if (label_len > 16) {
		ERROR("FS label is longer than allowed by filesystem\n");
		goto out;
		}


		blockdir = opendir("/dev/block");
		if (!blockdir) {
		ERROR("couldn't open /dev/block\n");
		goto out;
		}

		while ((ent = readdir(blockdir))) {
		int fd;
		char super_buf[1024];
		struct ext4_super_block *sb;

		if (ent->d_type != DT_BLK)
		continue;

		fd = openat(dirfd(blockdir), ent->d_name, O_RDONLY);
		if (fd < 0) {
		ERROR("Cannot open block device /dev/block/%s\n", ent->d_name);
		goto out;
		}

		if (TEMP_FAILURE_RETRY(lseek(fd, 1024, SEEK_SET)) < 0 \|\|
		TEMP_FAILURE_RETRY(read(fd, super_buf, 1024)) != 1024) {
		/* Probably a loopback device or something else without a readable
		* superblock.
		*/
		close(fd);
		continue;
		}

		sb = (struct ext4_super_block *)super_buf;
		if (sb->s_magic != EXT4_SUPER_MAGIC) {
		INFO("/dev/block/%s not ext{234}\n", ent->d_name);
		continue;
		}

		if (!strncmp(label, sb->s_volume_name, label_len)) {
		char *new_blk_device;

		if (asprintf(&new_blk_device, "/dev/block/%s", ent->d_name) < 0) {
		ERROR("Could not allocate block device string\n");
		goto out;
		}

		INFO("resolved label %s to %s\n", rec->blk_device, new_blk_device);

		free(rec->blk_device);
		rec->blk_device = new_blk_device;
		ret = 0;
		break;
		}
		}

		out:
		closedir(blockdir);
		return ret;
		}

		/* When multiple fstab records share the same mount_point, it will
		* try to mount each one in turn, and ignore any duplicates after a
		* first successful mount.
		@@ -356,6 +436,17 @@ int fs_mgr_mount_all(struct fstab *fstab)
		continue;
		}

		/* Translate LABEL= file system labels into block devices */
		if (!strcmp(fstab->recs[i].fs_type, "ext2") \|\|
		!strcmp(fstab->recs[i].fs_type, "ext3") \|\|
		!strcmp(fstab->recs[i].fs_type, "ext4")) {
		int tret = translate_ext_labels(&fstab->recs[i]);
		if (tret < 0) {
		ERROR("Could not translate label to block device\n");
		continue;
		}
		}

		if (fstab->recs[i].fs_mgr_flags & MF_WAIT) {
		wait_for_file(fstab->recs[i].blk_device, WAIT_TIMEOUT);
		}