Merge branch 'jh/fsck-promisors'

In preparation for implementing narrow/partial clone, the machinery
for checking object connectivity used by gc and fsck has been
taught that a missing object is OK when it is referenced by a
packfile specially marked as coming from trusted repository that
promises to make them available on-demand and lazily.

* jh/fsck-promisors:
  gc: do not repack promisor packfiles
  rev-list: support termination at promisor objects
  sha1_file: support lazily fetching missing objects
  introduce fetch-object: fetch one promisor object
  index-pack: refactor writing of .keep files
  fsck: support promisor objects as CLI argument
  fsck: support referenced promisor objects
  fsck: support refs pointing to promisor objects
  fsck: introduce partialclone extension
  extension.partialclone: introduce partial clone extension

4 files changed, 41 insertions, 0 deletions

diff --git a/Documentation/git-pack-objects.txt b/Documentation/git-pack-objects.txt
index aa403d02f3..81bc490ac5 100644
--- a/Documentation/git-pack-objects.txt
+++ b/Documentation/git-pack-objects.txt
@@ -255,6 +255,17 @@ a missing object is encountered.  This is the default action.
 The form '--missing=allow-any' will allow object traversal to continue
 if a missing object is encountered.  Missing objects will silently be
 omitted from the results.
++
+The form '--missing=allow-promisor' is like 'allow-any', but will only
+allow object traversal to continue for EXPECTED promisor missing objects.
+Unexpected missing object will raise an error.
+
+--exclude-promisor-objects::
+	Omit objects that are known to be in the promisor remote.  (This
+	option has the purpose of operating only on locally created objects,
+	so that when we repack, we still maintain a distinction between
+	locally created objects [without .promisor] and objects from the
+	promisor remote [with .promisor].)  This is used with partial clone.
 
 SEE ALSO
 --------
diff --git a/Documentation/gitremote-helpers.txt b/Documentation/gitremote-helpers.txt
index 4a584f3c5d..4b8c93ec59 100644
--- a/Documentation/gitremote-helpers.txt
+++ b/Documentation/gitremote-helpers.txt
@@ -466,6 +466,13 @@ set by Git if the remote helper has the 'option' capability.
 	Transmit <string> as a push option. As the push option
 	must not contain LF or NUL characters, the string is not encoded.
 
+'option from-promisor' {'true'|'false'}::
+	Indicate that these objects are being fetched from a promisor.
+
+'option no-dependents' {'true'|'false'}::
+	Indicate that only the objects wanted need to be fetched, not
+	their dependents.
+
 SEE ALSO
 --------
 linkgit:git-remote[1]
diff --git a/Documentation/rev-list-options.txt b/Documentation/rev-list-options.txt
index 22f5c9b43d..7b273635de 100644
--- a/Documentation/rev-list-options.txt
+++ b/Documentation/rev-list-options.txt
@@ -750,10 +750,21 @@ The form '--missing=allow-any' will allow object traversal to continue
 if a missing object is encountered.  Missing objects will silently be
 omitted from the results.
 +
+The form '--missing=allow-promisor' is like 'allow-any', but will only
+allow object traversal to continue for EXPECTED promisor missing objects.
+Unexpected missing objects will raise an error.
++
 The form '--missing=print' is like 'allow-any', but will also print a
 list of the missing objects.  Object IDs are prefixed with a ``?'' character.
 endif::git-rev-list[]
 
+--exclude-promisor-objects::
+	(For internal use only.)  Prefilter object traversal at
+	promisor boundary.  This is used with partial clone.  This is
+	stronger than `--missing=allow-promisor` because it limits the
+	traversal, rather than just silencing errors about missing
+	objects.
+
 --no-walk[=(sorted|unsorted)]::
 	Only show the given commits, but do not traverse their ancestors.
 	This has no effect if a range is specified. If the argument
diff --git a/Documentation/technical/repository-version.txt b/Documentation/technical/repository-version.txt
index 00ad37986e..e03eaccebc 100644
--- a/Documentation/technical/repository-version.txt
+++ b/Documentation/technical/repository-version.txt
@@ -86,3 +86,15 @@ for testing format-1 compatibility.
 When the config key `extensions.preciousObjects` is set to `true`,
 objects in the repository MUST NOT be deleted (e.g., by `git-prune` or
 `git repack -d`).
+
+`partialclone`
+~~~~~~~~~~~~~~
+
+When the config key `extensions.partialclone` is set, it indicates
+that the repo was created with a partial clone (or later performed
+a partial fetch) and that the remote may have omitted sending
+certain unwanted objects.  Such a remote is called a "promisor remote"
+and it promises that all such omitted objects can be fetched from it
+in the future.
+
+The value of this key is the name of the promisor remote.