deal with ignoreinode config setting

Improve handling of directory special remotes with importtree=yes whose
ignoreinode setting has been changed. (By either enableremote or by
upgrading to commit 3e2f1f73cb.)

When getting a file from such a remote, accept the content that would have
been accepted with the previous ignoreinode setting.

After a change to ignoreinode, importing a tree from the remote will
re-import and generate new content identifiers using the new config. So
when ignoreinode has changed to no, the inodes will be learned, and after
that point, a change in an inode will be detected as a change. Before
re-importing, a change in an inode will be ignored, as it was before the
ignoreinode change. This seems acceptble, because the user can re-import
immediately if they urgently need to add inodes. And if not, they'll
do it sometime, presumably, and the change will take effect then.

Sponsored-by: Erik Bjäreholt on Patreon

CHANGELOG

@@ -13,6 +13,10 @@ git-annex (10.20220823) UNRELEASED; urgency=medium
     all keys via --all or in a bare repo.
     (Introduced in version 8.20200720)
   * vicfg: Include mincopies configuration.
+  * Improve handling of directory special remotes with importtree=yes whose
+    ignoreinode setting has been changed. When getting a file from such a
+    remote, accept the content that would have been accepted with the
+    previous ignoreinode setting.
 
  -- Joey Hess <id@joeyh.name>  Mon, 29 Aug 2022 15:03:04 -0400
 

Remote/Directory.hs

@@ -390,10 +390,24 @@ mkContentIdentifier (IgnoreInodes ii) f st =
 			then toInodeCache' noTSDelta f st 0
 			else toInodeCache noTSDelta f st
 
+-- Since ignoreinodes can be changed by enableremote, and since previous
+-- versions of git-annex ignored inodes by default, treat two content
+-- idenfiers as the same if they differ only by one having the inode
+-- ignored.
 guardSameContentIdentifiers :: a -> ContentIdentifier -> Maybe ContentIdentifier -> a
-guardSameContentIdentifiers cont old new
-	| new == Just old = cont
+guardSameContentIdentifiers _ _ Nothing = giveup "file not found"
+guardSameContentIdentifiers cont old (Just new)
+	| new == old = cont
+	| ignoreinode new == old = cont
+	| new == ignoreinode old = cont
 	| otherwise = giveup "file content has changed"
+  where
+	ignoreinode cid@(ContentIdentifier b) = 
+		case readInodeCache (decodeBS b) of
+			Nothing -> cid
+			Just ic -> 
+				let ic' = replaceInode 0 ic
+				in ContentIdentifier (encodeBS (showInodeCache ic'))
 
 importKeyM :: IgnoreInodes -> RawFilePath -> ExportLocation -> ContentIdentifier -> ByteSize -> MeterUpdate -> Annex (Maybe Key)
 importKeyM ii dir loc cid sz p = do

Utility/InodeCache.hs

@@ -32,6 +32,7 @@ module Utility.InodeCache (
 	inodeCacheToMtime,
 	inodeCacheToEpochTime,
 	inodeCacheEpochTimeRange,
+	replaceInode,
 
 	SentinalFile(..),
 	SentinalStatus(..),
@@ -125,6 +126,10 @@ inodeCacheEpochTimeRange i =
 	let t = inodeCacheToEpochTime i
 	in (t-1, t+1)
 
+replaceInode :: FileID -> InodeCache -> InodeCache
+replaceInode inode (InodeCache (InodeCachePrim _ sz mtime)) =
+	InodeCache (InodeCachePrim inode sz mtime)
+
 {- For backwards compatability, support low-res mtime with no
  - fractional seconds. -}
 data MTime = MTimeLowRes EpochTime | MTimeHighRes POSIXTime

doc/bugs/Incorrect___34__file_content_has_changed__34___on_duplicates/comment_3_a99df351ed700f908b6aaf3f52d245b4._comment

@@ -0,0 +1,9 @@
+[[!comment format=mdwn
+ username="joey"
+ subject="""comment 3"""
+ date="2022-09-16T17:43:38Z"
+ content="""
+I've made the directory special remote treat content identifiers
+that differ only in one having the inode set to 0. Which will avoid it
+failing in the situation I showed.
+"""]]