btrfs-check: add page (#6959)

pages/linux/btrfs-check.md

@@ -0,0 +1,32 @@
+# btrfs check
+
+> Check or repair a btrfs filesystem.
+> More information: <https://btrfs.wiki.kernel.org/index.php/Manpage/btrfs-check>.
+
+- Check a btrfs filesystem:
+
+`sudo btrfs check {{path/to/partition}}`
+
+- Check and repair a btrfs filesystem (dangerous):
+
+`sudo btrfs check --repair {{path/to/partition}}`
+
+- Show the progress of the check:
+
+`sudo btrfs check --progress {{path/to/partition}}`
+
+- Verify the checksum of each data block (if the filesystem is good):
+
+`sudo btrfs check --check-data-csum {{path/to/partition}}`
+
+- Use the `n`-th superblock (`n` can be 0, 1 or 2):
+
+`sudo btrfs check --super {{n}} {{path/to/partition}}`
+
+- Rebuild the checksum tree:
+
+`sudo btrfs check --repair --init-csum-tree {{path/to/partition}}`
+
+- Rebuild the extent tree:
+
+`sudo btrfs check --repair --init-extent-tree {{path/to/partition}}`