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Scan /dev/md and device mapper devices last 

When we're using multipath or raid0, it is possible
that btrfs dev scan will find one of the component devices
instead of the proper virtual device the kernel creates.

We want to make sure the kernel scans the virtual devices last,
since it always remembers the last device it finds with a given fsid.

Signed-off-by: Chris Mason <chris.mason@oracle.com>
master
Chris Mason 2012-02-21 15:56:10 -05:00
parent 32eff71182
commit 8f01235dd8
2 changed files with 32 additions and 2 deletions
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25
utils.c
View File

@ -1138,7 +1138,10 @@ int btrfs_scan_block_devices(int run_ioctl)
int i;
char buf[1024];
char fullpath[110];
int scans = 0;
int special;
scan_again:
proc_partitions = fopen("/proc/partitions","r");
if (!proc_partitions) {
fprintf(stderr, "Unable to open '/proc/partitions' for scanning\n");
@ -1154,8 +1157,23 @@ int btrfs_scan_block_devices(int run_ioctl)
strcpy(fullpath,"/dev/");
while(fgets(buf, 1023, proc_partitions)) {
i = sscanf(buf," %*d %*d %*d %99s", fullpath+5);
/*
* multipath and MD devices may register as a btrfs filesystem
* both through the original block device and through
* the special (/dev/mapper or /dev/mdX) entry.
* This scans the special entries last
*/
special = strncmp(fullpath, "/dev/dm-", strlen("/dev/dm-")) == 0;
if (!special)
special = strncmp(fullpath, "/dev/md", strlen("/dev/md")) == 0;
if (scans == 0 && special)
continue;
if (scans > 0 && !special)
continue;
ret = lstat(fullpath, &st);
if (ret < 0) {
fprintf(stderr, "failed to stat %s\n", fullpath);
@ -1180,6 +1198,11 @@ int btrfs_scan_block_devices(int run_ioctl)
}
fclose(proc_partitions);
if (scans == 0) {
scans++;
goto scan_again;
}
return 0;
}

9
volumes.c
View File

@ -128,7 +128,14 @@ static int device_list_add(const char *path,
btrfs_stack_device_bytes_used(&disk_super->dev_item);
list_add(&device->dev_list, &fs_devices->devices);
device->fs_devices = fs_devices;
}
} else if (!device->name || strcmp(device->name, path)) {
char *name = strdup(path);
if (!name)
return -ENOMEM;
kfree(device->name);
device->name = name;
}
if (found_transid > fs_devices->latest_trans) {
fs_devices->latest_devid = devid;