From: Tobias Jakobi <tjakobi@math.uni-bielefeld.de>
Date: Wed, 28 Sep 2016 17:28:03 +0000 (+0200)
Subject: libf2fs: increase robustness when called on root device
X-Git-Tag: v1.8.0~58
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=e5b3ec89eec84e9d073788e6169b464169305026;p=platform%2Fupstream%2Ff2fs-tools.git

libf2fs: increase robustness when called on root device

On some systems '/proc/mounts' contains the entry '/dev/root'
as alias for the root device, while that alias doesn't actually
exist as symlink in /dev.

/proc/mounts:
/dev/root / f2fs rw,noatime,background_gc=on,user_xattr,acl,inline_data,extent_cache,active_logs=6 0 0

mount:
/dev/mmcblk1p1 on / type f2fs (rw,noatime,background_gc=on,user_xattr,acl,inline_data,extent_cache,active_logs=6)

If the root device is mounted RO, and we try to scan it, via
'fsck.f2fs /dev/mmcblk1p1', then fsck.f2fs exits because it can't
find the entry in /proc/mounts.

Try harder to identify the root device of the system first, and
in case we are operating on it, check also for '/dev/root' in mounts.

Signed-off-by: Tobias Jakobi <tjakobi@math.uni-bielefeld.de>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
---

diff --git a/include/f2fs_fs.h b/include/f2fs_fs.h
index 19ce250..bfe9b3f 100644
--- a/include/f2fs_fs.h
+++ b/include/f2fs_fs.h
@@ -279,6 +279,7 @@ struct f2fs_configuration {
 	int32_t dump_fd;
 	char *device_name;
 	char *extension_list;
+	const char *rootdev_name;
 	int dbg_lv;
 	int trim;
 	int func;
diff --git a/lib/libf2fs.c b/lib/libf2fs.c
index 2284a78..6140452 100644
--- a/lib/libf2fs.c
+++ b/lib/libf2fs.c
@@ -21,6 +21,7 @@
 #include <sys/ioctl.h>
 #include <scsi/sg.h>
 #include <linux/hdreg.h>
+#include <linux/limits.h>
 
 #include <f2fs_fs.h>
 
@@ -485,6 +486,53 @@ int f2fs_crc_valid(u_int32_t blk_crc, void *buf, int len)
 }
 
 /*
+ * try to identify the root device
+ */
+const char *get_rootdev()
+{
+	struct stat sb;
+	int fd, ret;
+	char buf[32];
+	char *uevent, *ptr;
+
+	static char rootdev[PATH_MAX + 1];
+
+	if (stat("/", &sb) == -1)
+		return NULL;
+
+	snprintf(buf, 32, "/sys/dev/block/%u:%u/uevent",
+		major(sb.st_dev), minor(sb.st_dev));
+
+	fd = open(buf, O_RDONLY);
+
+	if (fd < 0)
+		return NULL;
+
+	ret = lseek(fd, (off_t)0, SEEK_END);
+	(void)lseek(fd, (off_t)0, SEEK_SET);
+
+	if (ret == -1) {
+		close(fd);
+		return NULL;
+	}
+
+	uevent = malloc(ret + 1);
+	uevent[ret] = '\0';
+
+	ret = read(fd, uevent, ret);
+	close(fd);
+
+	ptr = strstr(uevent, "DEVNAME");
+	if (!ptr)
+		return NULL;
+
+	ret = sscanf(ptr, "DEVNAME=%s\n", buf);
+	snprintf(rootdev, PATH_MAX + 1, "/dev/%s", buf);
+
+	return rootdev;
+}
+
+/*
  * device information
  */
 void f2fs_init_configuration(void)
@@ -493,6 +541,7 @@ void f2fs_init_configuration(void)
 	c.sector_size = DEFAULT_SECTOR_SIZE;
 	c.sectors_per_blk = DEFAULT_SECTORS_PER_BLOCK;
 	c.blks_per_seg = DEFAULT_BLOCKS_PER_SEGMENT;
+	c.rootdev_name = get_rootdev();
 
 	/* calculated by overprovision ratio */
 	c.reserved_segments = 0;
@@ -532,8 +581,12 @@ static int is_mounted(const char *mpt, const char *device)
 int f2fs_dev_is_umounted(void)
 {
 	struct stat st_buf;
+	int is_rootdev = 0;
 	int ret = 0;
 
+	if (c.rootdev_name && !strcmp(c.device_name, c.rootdev_name))
+		is_rootdev = 1;
+
 	/*
 	 * try with /proc/mounts fist to detect RDONLY.
 	 * f2fs_stop_checkpoint makes RO in /proc/mounts while RW in /etc/mtab.
@@ -551,6 +604,19 @@ int f2fs_dev_is_umounted(void)
 	}
 
 	/*
+	 * If we are supposed to operate on the root device, then
+	 * also check the mounts for '/dev/root', which sometimes
+	 * functions as an alias for the root device.
+	 */
+	if (is_rootdev) {
+		ret = is_mounted("/proc/mounts", "/dev/root");
+		if (ret) {
+			MSG(0, "Info: Mounted device!\n");
+			return -1;
+		}
+	}
+
+	/*
 	 * If f2fs is umounted with -l, the process can still use
 	 * the file system. In this case, we should not format.
 	 */