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authorTobias Geerinckx-Rice <me@tobias.gr>2020-11-05 13:06:18 +0100
committerTobias Geerinckx-Rice <me@tobias.gr>2020-11-07 13:40:45 +0100
commit174254749da64a92192ccfb5239867be30fed4ea (patch)
treea0a33885d7667cf884f15d86d48f1f58fd81b345
parentc073efc91c93adea27182c54ed1e9f558d26ef20 (diff)
file-systems: Add support for bcachefs.
* gnu/build/file-systems.scm (%bcachefs-endianness): New syntax. (bcachefs-superblock?, read-bcachefs-superblock) (bcachefs-superblock-external-uuid, bcachefs-superblock-volume-name) (check-bcachefs-file-system): New procedures. (%partition-label-readers, %partition-uuid-readers, check-file-system): Register them.
-rw-r--r--gnu/build/file-systems.scm59
1 files changed, 58 insertions, 1 deletions
diff --git a/gnu/build/file-systems.scm b/gnu/build/file-systems.scm
index 8ec8eac896..b762e82ad2 100644
--- a/gnu/build/file-systems.scm
+++ b/gnu/build/file-systems.scm
@@ -3,7 +3,7 @@
;;; Copyright © 2016, 2017 David Craven <david@craven.ch>
;;; Copyright © 2017 Mathieu Othacehe <m.othacehe@gmail.com>
;;; Copyright © 2019 Guillaume Le Vaillant <glv@posteo.net>
-;;; Copyright © 2019 Tobias Geerinckx-Rice <me@tobias.gr>
+;;; Copyright © 2019, 2020 Tobias Geerinckx-Rice <me@tobias.gr>
;;; Copyright © 2019 David C. Trudgian <dave@trudgian.net>
;;; Copyright © 2020 Maxim Cournoyer <maxim.cournoyer@gmail.com>
;;;
@@ -218,6 +218,58 @@ if DEVICE does not contain an linux-swap file system."
"Return the label of Linux-swap superblock SBLOCK as a string."
(null-terminated-latin1->string
(sub-bytevector sblock (+ 1024 4 4 4 16) 16)))
+
+
+;;;
+;;; Bcachefs file systems.
+;;;
+
+;; <https://evilpiepirate.org/git/bcachefs-tools.git/tree/libbcachefs/bcachefs_format.h>
+
+(define-syntax %bcachefs-endianness
+ ;; Endianness of bcachefs file systems.
+ (identifier-syntax (endianness little)))
+
+(define (bcachefs-superblock? sblock)
+ "Return #t when SBLOCK is an bcachefs superblock."
+ (bytevector=? (sub-bytevector sblock 24 16)
+ #vu8(#xc6 #x85 #x73 #xf6 #x4e #x1a #x45 #xca
+ #x82 #x65 #xf5 #x7f #x48 #xba #x6d #x81)))
+
+(define (read-bcachefs-superblock device)
+ "Return the raw contents of DEVICE's bcachefs superblock as a bytevector, or #f
+if DEVICE does not contain a bcachefs file system."
+ ;; We completely ignore the back-up superblock & any checksum errors.
+ ;; Superblock field names, with offset & length respectively, in bytes:
+ ;; 0 16 bch_csum
+ ;; 16 8 version
+ ;; 24 16 magic
+ ;; 40 16 uuid ← ‘internal UUID’, you probably don't want this
+ ;; 56 16 user_uuid ← ‘external UUID’, the one by which to mount
+ ;; 72 32 label
+ ;; … there are more & the superblock is extensible, but we don't care yet.
+ (read-superblock device 4096 104 bcachefs-superblock?))
+
+(define (bcachefs-superblock-external-uuid sblock)
+ "Return the external UUID of bcachefs superblock SBLOCK as a 16-byte
+bytevector."
+ (sub-bytevector sblock 56 16))
+
+(define (bcachefs-superblock-volume-name sblock)
+ "Return the volume name of SBLOCK as a string of at most 32 characters, or
+#f if SBLOCK has no volume name."
+ (null-terminated-latin1->string (sub-bytevector sblock 72 32)))
+
+(define (check-bcachefs-file-system device)
+ "Return the health of a bcachefs file system on DEVICE."
+ (match (status:exit-val
+ (apply system* "bcachefs" "fsck" "-p" "-v"
+ ;; Make each multi-device member a separate argument.
+ (string-split device #\:)))
+ (0 'pass)
+ (1 'errors-corrected)
+ (2 'reboot-required)
+ (_ 'fatal-error)))
;;;
@@ -638,6 +690,8 @@ partition field reader that returned a value."
ext2-superblock-volume-name)
(partition-field-reader read-linux-swap-superblock
linux-swap-superblock-volume-name)
+ (partition-field-reader read-bcachefs-superblock
+ bcachefs-superblock-volume-name)
(partition-field-reader read-btrfs-superblock
btrfs-superblock-volume-name)
(partition-field-reader read-fat32-superblock
@@ -656,6 +710,8 @@ partition field reader that returned a value."
ext2-superblock-uuid)
(partition-field-reader read-linux-swap-superblock
linux-swap-superblock-uuid)
+ (partition-field-reader read-bcachefs-superblock
+ bcachefs-superblock-external-uuid)
(partition-field-reader read-btrfs-superblock
btrfs-superblock-uuid)
(partition-field-reader read-fat32-superblock
@@ -763,6 +819,7 @@ containing ':/')."
(define check-procedure
(cond
((string-prefix? "ext" type) check-ext2-file-system)
+ ((string-prefix? "bcachefs" type) check-bcachefs-file-system)
((string-prefix? "btrfs" type) check-btrfs-file-system)
((string-suffix? "fat" type) check-fat-file-system)
((string-prefix? "jfs" type) check-jfs-file-system)