diff options
| -rw-r--r-- | guix/store/deduplication.scm | 40 | ||||
| -rw-r--r-- | tests/store-deduplication.scm | 44 |
2 files changed, 70 insertions, 14 deletions
diff --git a/guix/store/deduplication.scm b/guix/store/deduplication.scm index 21b0c81f3d..a777940f86 100644 --- a/guix/store/deduplication.scm +++ b/guix/store/deduplication.scm @@ -99,24 +99,38 @@ LINK-PREFIX." (define* (replace-with-link target to-replace #:key (swap-directory (dirname target))) "Atomically replace the file TO-REPLACE with a link to TARGET. Use -SWAP-DIRECTORY as the directory to store temporary hard links. +SWAP-DIRECTORY as the directory to store temporary hard links. Upon ENOSPC +and EMLINK, TO-REPLACE is left unchanged. Note: TARGET, TO-REPLACE, and SWAP-DIRECTORY must be on the same file system." - (let* ((temp-link (get-temp-link target swap-directory)) - (parent (dirname to-replace)) - (stat (stat parent))) - (make-file-writable parent) + (define temp-link (catch 'system-error (lambda () - (rename-file temp-link to-replace) - - ;; Restore PARENT's mtime and permissions. - (set-file-time parent stat) - (chmod parent (stat:mode stat))) + (get-temp-link target swap-directory)) (lambda args - (delete-file temp-link) - (unless (= EMLINK (system-error-errno args)) - (apply throw args)))))) + ;; We get ENOSPC when we can't fit an additional entry in + ;; SWAP-DIRECTORY. + (if (= ENOSPC (system-error-errno args)) + #f + (apply throw args))))) + + ;; If we couldn't create TEMP-LINK, that's OK: just don't do the + ;; replacement, which means TO-REPLACE won't be deduplicated. + (when temp-link + (let* ((parent (dirname to-replace)) + (stat (stat parent))) + (make-file-writable parent) + (catch 'system-error + (lambda () + (rename-file temp-link to-replace)) + (lambda args + (delete-file temp-link) + (unless (= EMLINK (system-error-errno args)) + (apply throw args)))) + + ;; Restore PARENT's mtime and permissions. + (set-file-time parent stat) + (chmod parent (stat:mode stat))))) (define* (deduplicate path hash #:key (store %store-directory)) "Check if a store item with sha256 hash HASH already exists. If so, diff --git a/tests/store-deduplication.scm b/tests/store-deduplication.scm index e438aa84c6..e2870a363d 100644 --- a/tests/store-deduplication.scm +++ b/tests/store-deduplication.scm @@ -48,7 +48,7 @@ (put-bytevector port data)))) identical) ;; Make the parent of IDENTICAL read-only. This should not prevent - ;; deduplication for inserting its hard link. + ;; deduplication from inserting its hard link. (chmod (dirname (second identical)) #o544) (call-with-output-file unique @@ -64,4 +64,46 @@ (stat:nlink (stat unique)) (map (compose stat:nlink stat) identical)))))) +(test-equal "deduplicate, ENOSPC" + (cons* #f ;inode comparison + (append (make-list 3 4) + (make-list 7 1))) ;'nlink' values + + ;; In this scenario the first 3 files are properly deduplicated and then we + ;; simulate a full '.links' directory where link(2) gets ENOSPC, thereby + ;; preventing deduplication of the subsequent files. + (call-with-temporary-directory + (lambda (store) + (let ((true-link link) + (links 0) + (data1 (string->utf8 "Hello, world!")) + (data2 (string->utf8 "Hi, world!")) + (identical (map (lambda (n) + (string-append store "/" (number->string n) + "/a/b/c")) + (iota 10))) + (populate (lambda (data) + (lambda (file) + (mkdir-p (dirname file)) + (call-with-output-file file + (lambda (port) + (put-bytevector port data))))))) + (for-each (populate data1) (take identical 5)) + (for-each (populate data2) (drop identical 5)) + (dynamic-wind + (lambda () + (set! link (lambda (old new) + (set! links (+ links 1)) + (if (<= links 3) + (true-link old new) + (throw 'system-error "link" "~A" '("Whaaat?!") + (list ENOSPC)))))) + (lambda () + (deduplicate store (nar-sha256 store) #:store store)) + (lambda () + (set! link true-link))) + + (cons (apply = (map (compose stat:ino stat) identical)) + (map (compose stat:nlink stat) identical)))))) + (test-end "store-deduplication") |