[PATCH v2 0/5] ref-transactions-rename

[PATCH v2 0/5] ref-transactions-rename

[Ronnie Sahlberg]

This patch series adds support for using transactions and atomic renames.
It focuses on what needs to be done in order to support fully atomic
and rollbackable renames that may or may not involve name conflicts.

By performing the actual delete old/create new via a single operation to
the packed refs file this process will also appear as an atomic change for
any external observers.

(While this series is "short" it contains a very important change where
we start performing ref changes as operations inside a locked packed refs
file instead of as discreete operations of loose ref files.
This approach will be extended in the next patch series where we will start
using it also to make multi-ref creations/updates become fully
atomic for external observers.)

Version 2:
 -- Updated with Jonathans suggestions from last week.


This series is built on iand depend on the previous reflog series:
  * rs/ref-transaction-reflog (2014-07-23) 15 commits
   - refs.c: allow deleting refs with a broken sha1
   - refs.c: remove lock_any_ref_for_update
   - refs.c: make unlock_ref/close_ref/commit_ref static
   - refs.c: rename log_ref_setup to create_reflog
   - reflog.c: use a reflog transaction when writing during expire
   - refs.c: allow multiple reflog updates during a single transaction
   - refs.c: only write reflog update if msg is non-NULL
   - refs.c: add a flag to allow reflog updates to truncate the log
   - refs.c: add a transaction function to append a reflog entry
   - lockfile.c: make hold_lock_file_for_append preserve meaningful errno
   - refs.c: add a function to append a reflog entry to a fd
   - refs.c: add a new update_type field to ref_update
   - refs.c: rename the transaction functions
   - refs.c: make ref_transaction_delete a wrapper for ref_transaction_update
   - refs.c: make ref_transaction_create a wrapper to ref_transaction_update
   (this branch uses rs/ref-transaction and rs/ref-transaction-1.)



Ronnie Sahlberg (5):
  refs.c: allow passing raw git_committer_info as email to
    _update_reflog
  refs.c: return error instead of dying when locking fails during
    transaction
  refs.c: use packed refs when deleting refs during a transaction
  refs.c: update rename_ref to use a transaction
  refs.c: rollback the lockfile before we die() in repack_without_refs

 builtin/reflog.c  |  19 ++-
 builtin/remote.c  |  14 +-
 refs.c            | 377 ++++++++++++++++++++++++++++++------------------------
 refs.h            |  25 +++-
 t/t3200-branch.sh |   7 -
 5 files changed, 255 insertions(+), 187 deletions(-)

-- 
2.0.1.523.g0041e8a

[PATCH v2 1/5] refs.c: allow passing raw git_committer_info as email to _update_reflog

[Ronnie Sahlberg]

In many places in the code we do not have access to the individual fields
in the committer data. Instead we might only have access to prebaked data
such as what is returned by git_committer_info() containing a string
that consists of email, timestamp, zone etc.

This makes it inconvenient to use transaction_update_reflog since it means
you would have to first parse git_committer_info before you can call
update_reflog.

Add a new flag REFLOG_COMMITTER_INFO_IS_VALID to _update_reflog to tell it
that we pass in a fully prebaked committer info string that can be used as is.

At the same time, also go over and change all references from email
to id where the code actually refers to a committer id and not just an email
address. I.e. where the string is : NAME <EMAIL>

Signed-off-by: Ronnie Sahlberg <sahlberg@google.com>
---
 builtin/reflog.c | 19 +++++++++++++------
 refs.c           | 21 ++++++++++++---------
 refs.h           | 25 +++++++++++++++++++++++--
 3 files changed, 48 insertions(+), 17 deletions(-)

diff --git a/builtin/reflog.c b/builtin/reflog.c
index f11fee3..c6f3a2f 100644
--- a/builtin/reflog.c
+++ b/builtin/reflog.c
@@ -292,7 +292,7 @@ static int unreachable(struct expire_reflog_cb *cb, struct commit *commit, unsig
 }
 
 static int expire_reflog_ent(unsigned char *osha1, unsigned char *nsha1,
-		const char *email, unsigned long timestamp, int tz,
+		const char *id, unsigned long timestamp, int tz,
 		const char *message, void *cb_data)
 {
 	struct expire_reflog_cb *cb = cb_data;
@@ -320,9 +320,14 @@ static int expire_reflog_ent(unsigned char *osha1, unsigned char *nsha1,
 		goto prune;
 
 	if (cb->t) {
+		struct reflog_committer_info ci;
+
+		memset(&ci, 0, sizeof(ci));
+		ci.id = id;
+		ci.timestamp = timestamp;
+		ci.tz = tz;
 		if (transaction_update_reflog(cb->t, cb->refname, nsha1, osha1,
-					      email, timestamp, tz, message, 0,
-					      &err))
+					      &ci, message, 0, &err))
 			return -1;
 		hashcpy(cb->last_kept_sha1, nsha1);
 	}
@@ -356,6 +361,7 @@ static int expire_reflog(const char *ref, const unsigned char *sha1, int unused,
 	struct expire_reflog_cb cb;
 	struct commit *tip_commit;
 	struct commit_list *tips;
+	struct reflog_committer_info ci;
 	int status = 0;
 
 	memset(&cb, 0, sizeof(cb));
@@ -368,9 +374,10 @@ static int expire_reflog(const char *ref, const unsigned char *sha1, int unused,
 		status |= error("%s", err.buf);
 		goto cleanup;
 	}
+
+	memset(&ci, 0, sizeof(ci));
 	if (transaction_update_reflog(cb.t, cb.refname, null_sha1, null_sha1,
-				      NULL, 0, 0, NULL, REFLOG_TRUNCATE,
-				      &err)) {
+				      &ci, NULL, REFLOG_TRUNCATE, &err)) {
 		status |= error("%s", err.buf);
 		goto cleanup;
 	}
@@ -671,7 +678,7 @@ static int cmd_reflog_expire(int argc, const char **argv, const char *prefix)
 }
 
 static int count_reflog_ent(unsigned char *osha1, unsigned char *nsha1,
-		const char *email, unsigned long timestamp, int tz,
+		const char *id, unsigned long timestamp, int tz,
 		const char *message, void *cb_data)
 {
 	struct cmd_reflog_expire_cb *cb = cb_data;
diff --git a/refs.c b/refs.c
index 2662ef6..41cb51d 100644
--- a/refs.c
+++ b/refs.c
@@ -3096,7 +3096,7 @@ struct read_ref_at_cb {
 };
 
 static int read_ref_at_ent(unsigned char *osha1, unsigned char *nsha1,
-		const char *email, unsigned long timestamp, int tz,
+		const char *id, unsigned long timestamp, int tz,
 		const char *message, void *cb_data)
 {
 	struct read_ref_at_cb *cb = cb_data;
@@ -3143,7 +3143,7 @@ static int read_ref_at_ent(unsigned char *osha1, unsigned char *nsha1,
 }
 
 static int read_ref_at_ent_oldest(unsigned char *osha1, unsigned char *nsha1,
-				  const char *email, unsigned long timestamp,
+				  const char *id, unsigned long timestamp,
 				  int tz, const char *message, void *cb_data)
 {
 	struct read_ref_at_cb *cb = cb_data;
@@ -3491,8 +3491,7 @@ int transaction_update_reflog(struct ref_transaction *transaction,
 			      const char *refname,
 			      const unsigned char *new_sha1,
 			      const unsigned char *old_sha1,
-			      const char *email,
-			      unsigned long timestamp, int tz,
+			      struct reflog_committer_info *ci,
 			      const char *msg, int flags,
 			      struct strbuf *err)
 {
@@ -3521,13 +3520,17 @@ int transaction_update_reflog(struct ref_transaction *transaction,
 	hashcpy(update->new_sha1, new_sha1);
 	hashcpy(update->old_sha1, old_sha1);
 	update->reflog_fd = -1;
-	if (email) {
+	if (flags & REFLOG_COMMITTER_INFO_IS_VALID) {
+		if (!ci->committer_info)
+			die("BUG: committer_info is NULL in reflog update");
+		update->committer = xstrdup(ci->committer_info);
+	} else if (ci->id) {
 		struct strbuf buf = STRBUF_INIT;
-		char sign = (tz < 0) ? '-' : '+';
-		int zone = (tz < 0) ? (-tz) : tz;
+		char sign = (ci->tz < 0) ? '-' : '+';
+		int zone = (ci->tz < 0) ? (-ci->tz) : ci->tz;
 
-		strbuf_addf(&buf, "%s %lu %c%04d", email, timestamp, sign,
-			    zone);
+		strbuf_addf(&buf, "%s %lu %c%04d", ci->id,
+			    ci->timestamp, sign, zone);
 		update->committer = xstrdup(buf.buf);
 		strbuf_release(&buf);
 	}
diff --git a/refs.h b/refs.h
index 0172f48..23067a2 100644
--- a/refs.h
+++ b/refs.h
@@ -309,6 +309,28 @@ int transaction_delete_sha1(struct ref_transaction *transaction,
  * Flags >= 0x100 are reserved for internal use.
  */
 #define REFLOG_TRUNCATE 0x01
+#define REFLOG_COMMITTER_INFO_IS_VALID 0x02
+
+/*
+ * Committer data provided to reflog updates.
+ * If flags contain REFLOG_COMMITTER_DATA_IS_VALID then
+ * then the structure contains a prebaked committer string
+ * just like git_committer_info() would return.
+ *
+ * If flags does not contain REFLOG_COMMITTER_DATA_IS_VALID
+ * then the committer info string will be generated using the passed
+ * email, timestamp and tz fields.
+ * This is useful for example from reflog iterators where you are passed
+ * these fields individually and not as a prebaked git_committer_info()
+ * string.
+ */
+struct reflog_committer_info {
+	const char *committer_info;
+
+	const char *id;
+	unsigned long timestamp;
+	int tz;
+};
 /*
  * Append a reflog entry for refname. If the REFLOG_TRUNCATE flag is set
  * this update will first truncate the reflog before writing the entry.
@@ -318,8 +340,7 @@ int transaction_update_reflog(struct ref_transaction *transaction,
 			      const char *refname,
 			      const unsigned char *new_sha1,
 			      const unsigned char *old_sha1,
-			      const char *email,
-			      unsigned long timestamp, int tz,
+			      struct reflog_committer_info *ci,
 			      const char *msg, int flags,
 			      struct strbuf *err);
 
-- 
2.0.1.523.g0041e8a

[PATCH v2 2/5] refs.c: return error instead of dying when locking fails during transaction

[Ronnie Sahlberg]

Change lock_ref_sha1_basic to return an error instead of dying when
we fail to lock a file during a transaction.
This function is only called from transaction_commit() and it knows how
to handle these failures.

Signed-off-by: Ronnie Sahlberg <sahlberg@google.com>
---
 refs.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/refs.c b/refs.c
index 41cb51d..35f6db1 100644
--- a/refs.c
+++ b/refs.c
@@ -2206,6 +2206,7 @@ static struct ref_lock *lock_ref_sha1_basic(const char *refname,
 
 	lock->lock_fd = hold_lock_file_for_update(lock->lk, ref_file, lflags);
 	if (lock->lock_fd < 0) {
+		last_errno = errno;
 		if (errno == ENOENT && --attempts_remaining > 0)
 			/*
 			 * Maybe somebody just deleted one of the
@@ -2213,8 +2214,10 @@ static struct ref_lock *lock_ref_sha1_basic(const char *refname,
 			 * again:
 			 */
 			goto retry;
-		else
-			unable_to_lock_index_die(ref_file, errno);
+		else {
+			unable_to_lock_error(ref_file, errno);
+			goto error_return;
+		}
 	}
 	if (bad_ref)
 		return lock;
-- 
2.0.1.523.g0041e8a

[PATCH v2 3/5] refs.c: use packed refs when deleting refs during a transaction

[Ronnie Sahlberg]

Make the deletion of refs during a transaction more atomic.
Start by first copying all loose refs we will be deleting to the packed
refs file and then commit the packed refs file. Then re-lock the packed refs
file to stop anyone else from modifying these refs and keep it locked until
we are finished.
Since all refs we are about to delete are now safely held in the packed refs
file we can proceed to immediately unlink any corresponding loose refs
and still be fully rollback-able.

The exception is for refs that can not be resolved. Those refs are never
added to the packed refs and will just be un-rollback-ably deleted during
commit.

By deleting all the loose refs at the start of the transaction we make make
it possible to both delete one ref and then re-create a different ref in
the same transaction even if the two refs would normally conflict.

Example: rename m->m/m

In that example we want to delete the file 'm' so that we make room so
that we can create a directory with the same name in order to lock and
write to the ref m/m and its lock-file m/m.lock.

If there is a failure during the commit phase we can rollback without losing
any refs since we have so far only deleted loose refs that that are
guaranteed to also have a corresponding entry in the packed refs file.
Once we have finished all updates for refs and their reflogs we can repack
the packed refs file and remove the to-be-deleted refs from the packed refs,
at which point all the deleted refs will disappear in one atomic rename
operation.

This also means that for an outside observer, deletion of multiple refs
in a single transaction will look atomic instead of one ref being deleted
at a time.

In order to do all this we need to change the semantics for the
repack_without_refs function so that we can lock the packed refs file,
do other stuff, and later be able to call repack_without_refs with the
lock already taken.
This means we need some additional changes in remote.c to reflect the
changes to the repack_without_refs semantics.

Signed-off-by: Ronnie Sahlberg <sahlberg@google.com>
---
 builtin/remote.c |  14 ++++--
 refs.c           | 148 +++++++++++++++++++++++++++++++++++++++++++------------
 2 files changed, 128 insertions(+), 34 deletions(-)

diff --git a/builtin/remote.c b/builtin/remote.c
index be8ebac..bfcc823 100644
--- a/builtin/remote.c
+++ b/builtin/remote.c
@@ -753,6 +753,9 @@ static int remove_branches(struct string_list *branches)
 	const char **branch_names;
 	int i, result = 0;
 
+	if (lock_packed_refs(0))
+		return unable_to_lock_error(git_path("packed-refs"), errno);
+
 	branch_names = xmalloc(branches->nr * sizeof(*branch_names));
 	for (i = 0; i < branches->nr; i++)
 		branch_names[i] = branches->items[i].string;
@@ -1333,9 +1336,14 @@ static int prune_remote(const char *remote, int dry_run)
 		delete_refs = xmalloc(states.stale.nr * sizeof(*delete_refs));
 		for (i = 0; i < states.stale.nr; i++)
 			delete_refs[i] = states.stale.items[i].util;
-		if (!dry_run)
-			result |= repack_without_refs(delete_refs,
-						      states.stale.nr, NULL);
+		if (!dry_run) {
+			if (lock_packed_refs(0))
+				result |= unable_to_lock_error(
+					git_path("packed-refs"), errno);
+			else
+				result |= repack_without_refs(delete_refs,
+							states.stale.nr, NULL);
+		}
 		free(delete_refs);
 	}
 
diff --git a/refs.c b/refs.c
index 35f6db1..32f48ea 100644
--- a/refs.c
+++ b/refs.c
@@ -2535,6 +2535,9 @@ static int curate_packed_ref_fn(struct ref_entry *entry, void *cb_data)
 	return 0;
 }
 
+/*
+ * Must be called with packed refs already locked (and sorted)
+ */
 int repack_without_refs(const char **refnames, int n, struct strbuf *err)
 {
 	struct ref_dir *packed;
@@ -2547,19 +2550,12 @@ int repack_without_refs(const char **refnames, int n, struct strbuf *err)
 		if (get_packed_ref(refnames[i]))
 			break;
 
-	/* Avoid locking if we have nothing to do */
-	if (i == n)
+	/* Avoid processing if we have nothing to do */
+	if (i == n) {
+		rollback_packed_refs();
 		return 0; /* no refname exists in packed refs */
-
-	if (lock_packed_refs(0)) {
-		if (err) {
-			unable_to_lock_message(git_path("packed-refs"), errno,
-					       err);
-			return -1;
-		}
-		unable_to_lock_error(git_path("packed-refs"), errno);
-		return error("cannot delete '%s' from packed refs", refnames[i]);
 	}
+
 	packed = get_packed_refs(&ref_cache);
 
 	/* Remove refnames from the cache */
@@ -3671,10 +3667,12 @@ static int ref_update_reject_duplicates(struct ref_update **updates, int n,
 int transaction_commit(struct ref_transaction *transaction,
 		       struct strbuf *err)
 {
-	int ret = 0, delnum = 0, i, df_conflict = 0;
+	int ret = 0, delnum = 0, i, df_conflict = 0, need_repack = 0;
 	const char **delnames;
 	int n = transaction->nr;
+	struct packed_ref_cache *packed_ref_cache;
 	struct ref_update **updates = transaction->updates;
+	struct ref_dir *packed;
 
 	if (transaction->state != REF_TRANSACTION_OPEN)
 		die("BUG: commit called for transaction that is not open");
@@ -3694,12 +3692,100 @@ int transaction_commit(struct ref_transaction *transaction,
 		goto cleanup;
 	}
 
-	/* Acquire all ref locks while verifying old values */
+	/* Lock packed refs during commit */
+	if (lock_packed_refs(0)) {
+		if (err)
+			unable_to_lock_message(git_path("packed-refs"),
+					       errno, err);
+		ret = -1;
+		goto cleanup;
+	}
+
+	/* any loose refs are to be deleted are first copied to packed refs */
+	for (i = 0; i < n; i++) {
+		struct ref_update *update = updates[i];
+		unsigned char sha1[20];
+
+		if (update->update_type != UPDATE_SHA1)
+			continue;
+		if (!is_null_sha1(update->new_sha1))
+			continue;
+		if (get_packed_ref(update->refname))
+			continue;
+		if (!resolve_ref_unsafe(update->refname, sha1, 1, NULL))
+			continue;
+
+		add_packed_ref(update->refname, sha1);
+		need_repack = 1;
+	}
+	if (need_repack) {
+		packed = get_packed_refs(&ref_cache);;
+		sort_ref_dir(packed);
+		if (commit_packed_refs()){
+			strbuf_addf(err, "unable to overwrite old ref-pack "
+				    "file");
+			ret = -1;
+			goto cleanup;
+		}
+		/* lock the packed refs again so no one can change it */
+		if (lock_packed_refs(0)) {
+			if (err)
+				unable_to_lock_message(git_path("packed-refs"),
+						       errno, err);
+			ret = -1;
+			goto cleanup;
+		}
+	}
+
+	/*
+	 * At this stage any refs that are to be deleted have been moved to the
+	 * packed refs file anf the packed refs file is deleted. We can now
+	 * safely delete these loose refs.
+	 */
+
+	/* Unlink any loose refs scheduled for deletion */
+	for (i = 0; i < n; i++) {
+		struct ref_update *update = updates[i];
+
+		if (update->update_type != UPDATE_SHA1)
+			continue;
+		if (!is_null_sha1(update->new_sha1))
+			continue;
+		update->lock = lock_ref_sha1_basic(update->refname,
+						   (update->have_old ?
+						    update->old_sha1 :
+						    NULL),
+						   update->flags,
+						   &update->type,
+						   delnames, delnum);
+		if (!update->lock) {
+			if (errno == ENOTDIR)
+				df_conflict = 1;
+			if (err)
+				strbuf_addf(err, "Cannot lock the ref '%s'.",
+					    update->refname);
+			ret = -1;
+			goto cleanup;
+		}
+		if (delete_ref_loose(update->lock, update->type, err)) {
+			ret = -1;
+			goto cleanup;
+		}
+		try_remove_empty_parents((char *)update->refname);
+		if (!(update->flags & REF_ISPRUNING))
+			  delnames[delnum++] = xstrdup(update->lock->ref_name);
+		unlock_ref(update->lock);
+		update->lock = NULL;
+	}
+
+	/* Acquire all ref locks for updates while verifying old values */
 	for (i = 0; i < n; i++) {
 		struct ref_update *update = updates[i];
 
 		if (update->update_type != UPDATE_SHA1)
 			continue;
+		if (is_null_sha1(update->new_sha1))
+			continue;
 		update->lock = lock_ref_sha1_basic(update->refname,
 						   (update->have_old ?
 						    update->old_sha1 :
@@ -3718,6 +3804,10 @@ int transaction_commit(struct ref_transaction *transaction,
 		}
 	}
 
+	/* delete reflog for all deleted refs */
+	for (i = 0; i < delnum; i++)
+		unlink_or_warn(git_path("logs/%s", delnames[i]));
+
 	/* Lock all reflog files */
 	for (i = 0; i < n; i++) {
 		struct ref_update *update = updates[i];
@@ -3729,6 +3819,16 @@ int transaction_commit(struct ref_transaction *transaction,
 			update->reflog_lock = update->orig_update->reflog_lock;
 			continue;
 		}
+		if (log_all_ref_updates && !reflog_exists(update->refname) &&
+		    create_reflog(update->refname)) {
+			ret = -1;
+			if (err)
+				strbuf_addf(err, "Failed to setup reflog for "
+					    "%s", update->refname);
+			goto cleanup;
+		}
+		if (!reflog_exists(update->refname))
+			continue;
 		update->reflog_fd = hold_lock_file_for_append(
 					update->reflog_lock,
 					git_path("logs/%s", update->refname),
@@ -3744,7 +3844,7 @@ int transaction_commit(struct ref_transaction *transaction,
 		}
 	}
 
-	/* Perform ref updates first so live commits remain referenced */
+	/* Perform ref updates */
 	for (i = 0; i < n; i++) {
 		struct ref_update *update = updates[i];
 
@@ -3765,21 +3865,6 @@ int transaction_commit(struct ref_transaction *transaction,
 		}
 	}
 
-	/* Perform deletes now that updates are safely completed */
-	for (i = 0; i < n; i++) {
-		struct ref_update *update = updates[i];
-
-		if (update->update_type != UPDATE_SHA1)
-			continue;
-		if (update->lock) {
-			if (delete_ref_loose(update->lock, update->type, err))
-				ret = -1;
-
-			if (!(update->flags & REF_ISPRUNING))
-				delnames[delnum++] = update->lock->ref_name;
-		}
-	}
-
 	/*
 	 * Update all reflog files
 	 * We have already committed all ref updates and deletes.
@@ -3832,11 +3917,12 @@ int transaction_commit(struct ref_transaction *transaction,
 
 	if (repack_without_refs(delnames, delnum, err))
 		ret = -1;
-	for (i = 0; i < delnum; i++)
-		unlink_or_warn(git_path("logs/%s", delnames[i]));
 	clear_loose_ref_cache(&ref_cache);
 
 cleanup:
+	packed_ref_cache = get_packed_ref_cache(&ref_cache);
+	if (packed_ref_cache->lock)
+		rollback_packed_refs();
 	transaction->state = ret ? REF_TRANSACTION_ERROR
 		: REF_TRANSACTION_CLOSED;
 
-- 
2.0.1.523.g0041e8a

[PATCH v2 4/5] refs.c: update rename_ref to use a transaction

[Ronnie Sahlberg]

Change refs.c to use a single transaction to copy/rename both the refs and
its reflog. Since we are no longer using rename() to move the reflog file
we no longer need to disallow rename_ref for refs with a symlink for its
reflog so we can remove that test from the testsuite.

Change the function to return 1 on failure instead of either -1 or 1.

These changes make the rename_ref operation atomic. This also eliminates the
need to use rename() to shift the reflog around via a temporary filename.
As an extension to this, since we no longer use rename() on the reflog file,
we can now safely perform renames even if the reflog is a symbolic link
and thus can remove the check and fail for that condition.

Signed-off-by: Ronnie Sahlberg <sahlberg@google.com>
---
 refs.c            | 197 ++++++++++++++++++++----------------------------------
 t/t3200-branch.sh |   7 --
 2 files changed, 71 insertions(+), 133 deletions(-)

diff --git a/refs.c b/refs.c
index 32f48ea..9c813f9 100644
--- a/refs.c
+++ b/refs.c
@@ -2620,82 +2620,52 @@ int delete_ref(const char *refname, const unsigned char *sha1, int delopt)
 	return 0;
 }
 
-/*
- * People using contrib's git-new-workdir have .git/logs/refs ->
- * /some/other/path/.git/logs/refs, and that may live on another device.
- *
- * IOW, to avoid cross device rename errors, the temporary renamed log must
- * live into logs/refs.
- */
-#define TMP_RENAMED_LOG  "logs/refs/.tmp-renamed-log"
+struct rename_reflog_cb {
+	struct ref_transaction *transaction;
+	const char *refname;
+	struct strbuf *err;
+};
 
-static int rename_tmp_log(const char *newrefname)
+static int rename_reflog_ent(unsigned char *osha1, unsigned char *nsha1,
+			     const char *id, unsigned long timestamp, int tz,
+			     const char *message, void *cb_data)
 {
-	int attempts_remaining = 4;
+	struct rename_reflog_cb *cb = cb_data;
+	struct reflog_committer_info ci;
 
- retry:
-	switch (safe_create_leading_directories(git_path("logs/%s", newrefname))) {
-	case SCLD_OK:
-		break; /* success */
-	case SCLD_VANISHED:
-		if (--attempts_remaining > 0)
-			goto retry;
-		/* fall through */
-	default:
-		error("unable to create directory for %s", newrefname);
-		return -1;
-	}
-
-	if (rename(git_path(TMP_RENAMED_LOG), git_path("logs/%s", newrefname))) {
-		if ((errno==EISDIR || errno==ENOTDIR) && --attempts_remaining > 0) {
-			/*
-			 * rename(a, b) when b is an existing
-			 * directory ought to result in ISDIR, but
-			 * Solaris 5.8 gives ENOTDIR.  Sheesh.
-			 */
-			if (remove_empty_directories(git_path("logs/%s", newrefname))) {
-				error("Directory not empty: logs/%s", newrefname);
-				return -1;
-			}
-			goto retry;
-		} else if (errno == ENOENT && --attempts_remaining > 0) {
-			/*
-			 * Maybe another process just deleted one of
-			 * the directories in the path to newrefname.
-			 * Try again from the beginning.
-			 */
-			goto retry;
-		} else {
-			error("unable to move logfile "TMP_RENAMED_LOG" to logs/%s: %s",
-				newrefname, strerror(errno));
-			return -1;
-		}
-	}
-	return 0;
+	memset(&ci, 0, sizeof(ci));
+	ci.id = id;
+	ci.timestamp = timestamp;
+	ci.tz = tz;
+	return transaction_update_reflog(cb->transaction, cb->refname,
+					 nsha1, osha1, &ci, message, 0,
+					 cb->err);
 }
 
-static int write_ref_sha1(struct ref_lock *lock, const unsigned char *sha1,
-			  const char *logmsg);
-
 int rename_ref(const char *oldrefname, const char *newrefname, const char *logmsg)
 {
-	unsigned char sha1[20], orig_sha1[20];
-	int flag = 0, logmoved = 0;
-	struct ref_lock *lock;
-	struct stat loginfo;
-	int log = !lstat(git_path("logs/%s", oldrefname), &loginfo);
+	unsigned char sha1[20];
+	int flag = 0, log;
+	struct ref_transaction *transaction = NULL;
+	struct strbuf err = STRBUF_INIT;
 	const char *symref = NULL;
+	struct rename_reflog_cb cb;
+	struct reflog_committer_info ci;
 
-	if (log && S_ISLNK(loginfo.st_mode))
-		return error("reflog for %s is a symlink", oldrefname);
+	memset(&ci, 0, sizeof(ci));
+	ci.committer_info = git_committer_info(0);
 
-	symref = resolve_ref_unsafe(oldrefname, orig_sha1,
+	symref = resolve_ref_unsafe(oldrefname, sha1,
 				    RESOLVE_REF_READING, &flag);
-	if (flag & REF_ISSYMREF)
-		return error("refname %s is a symbolic ref, renaming it is not supported",
+	if (flag & REF_ISSYMREF) {
+		error("refname %s is a symbolic ref, renaming it is not supported",
 			oldrefname);
-	if (!symref)
-		return error("refname %s not found", oldrefname);
+		return 1;
+	}
+	if (!symref) {
+		error("refname %s not found", oldrefname);
+		return 1;
+	}
 
 	if (!is_refname_available(newrefname, get_packed_refs(&ref_cache),
 				  &oldrefname, 1))
@@ -2705,70 +2675,45 @@ int rename_ref(const char *oldrefname, const char *newrefname, const char *logms
 				  &oldrefname, 1))
 		return 1;
 
-	if (log && rename(git_path("logs/%s", oldrefname), git_path(TMP_RENAMED_LOG)))
-		return error("unable to move logfile logs/%s to "TMP_RENAMED_LOG": %s",
-			oldrefname, strerror(errno));
-
-	if (delete_ref(oldrefname, orig_sha1, REF_NODEREF)) {
-		error("unable to delete old %s", oldrefname);
-		goto rollback;
-	}
-
-	if (!read_ref_full(newrefname, sha1, RESOLVE_REF_READING, NULL) &&
-	    delete_ref(newrefname, sha1, REF_NODEREF)) {
-		if (errno==EISDIR) {
-			if (remove_empty_directories(git_path("%s", newrefname))) {
-				error("Directory not empty: %s", newrefname);
-				goto rollback;
-			}
-		} else {
-			error("unable to delete existing %s", newrefname);
-			goto rollback;
-		}
-	}
-
-	if (log && rename_tmp_log(newrefname))
-		goto rollback;
-
-	logmoved = log;
-
-	lock = lock_ref_sha1_basic(newrefname, NULL, 0, NULL, NULL, 0);
-	if (!lock) {
-		error("unable to lock %s for update", newrefname);
-		goto rollback;
-	}
-	lock->force_write = 1;
-	hashcpy(lock->old_sha1, orig_sha1);
-	if (write_ref_sha1(lock, orig_sha1, logmsg)) {
-		error("unable to write current sha1 into %s", newrefname);
-		goto rollback;
-	}
-
+	log = reflog_exists(oldrefname);
+	transaction = transaction_begin(&err);
+	if (!transaction)
+		goto fail;
+
+	if (strcmp(oldrefname, newrefname)) {
+		if (log && transaction_update_reflog(transaction, newrefname,
+						     sha1, sha1, &ci, NULL,
+						     REFLOG_TRUNCATE, &err))
+			goto fail;
+		cb.transaction = transaction;
+		cb.refname = newrefname;
+		cb.err = &err;
+		if (log && for_each_reflog_ent(oldrefname, rename_reflog_ent,
+					       &cb))
+			goto fail;
+
+		if (transaction_delete_sha1(transaction, oldrefname, sha1,
+					    REF_NODEREF,
+					    1, NULL, &err))
+			goto fail;
+	}
+	if (transaction_update_sha1(transaction, newrefname, sha1,
+				    NULL, 0, 0, NULL, &err))
+		goto fail;
+	if (log && transaction_update_reflog(transaction, newrefname, sha1,
+					     sha1, &ci, logmsg,
+					     REFLOG_COMMITTER_INFO_IS_VALID,
+					     &err))
+		goto fail;
+	if (transaction_commit(transaction, &err))
+		goto fail;
+	transaction_free(transaction);
 	return 0;
 
- rollback:
-	lock = lock_ref_sha1_basic(oldrefname, NULL, 0, NULL, NULL, 0);
-	if (!lock) {
-		error("unable to lock %s for rollback", oldrefname);
-		goto rollbacklog;
-	}
-
-	lock->force_write = 1;
-	flag = log_all_ref_updates;
-	log_all_ref_updates = 0;
-	if (write_ref_sha1(lock, orig_sha1, NULL))
-		error("unable to write current sha1 into %s", oldrefname);
-	log_all_ref_updates = flag;
-
- rollbacklog:
-	if (logmoved && rename(git_path("logs/%s", newrefname), git_path("logs/%s", oldrefname)))
-		error("unable to restore logfile %s from %s: %s",
-			oldrefname, newrefname, strerror(errno));
-	if (!logmoved && log &&
-	    rename(git_path(TMP_RENAMED_LOG), git_path("logs/%s", oldrefname)))
-		error("unable to restore logfile %s from "TMP_RENAMED_LOG": %s",
-			oldrefname, strerror(errno));
-
+ fail:
+	error("rename_ref failed: %s", err.buf);
+	strbuf_release(&err);
+	transaction_free(transaction);
 	return 1;
 }
 
diff --git a/t/t3200-branch.sh b/t/t3200-branch.sh
index ac31b71..64f5bf2 100755
--- a/t/t3200-branch.sh
+++ b/t/t3200-branch.sh
@@ -293,13 +293,6 @@ test_expect_success 'renaming a symref is not allowed' '
 	test_path_is_missing .git/refs/heads/master3
 '
 
-test_expect_success SYMLINKS 'git branch -m u v should fail when the reflog for u is a symlink' '
-	git branch -l u &&
-	mv .git/logs/refs/heads/u real-u &&
-	ln -s real-u .git/logs/refs/heads/u &&
-	test_must_fail git branch -m u v
-'
-
 test_expect_success 'test tracking setup via --track' '
 	git config remote.local.url . &&
 	git config remote.local.fetch refs/heads/*:refs/remotes/local/* &&
-- 
2.0.1.523.g0041e8a

[PATCH v2 5/5] refs.c: rollback the lockfile before we die() in repack_without_refs

[Ronnie Sahlberg]

Signed-off-by: Ronnie Sahlberg <sahlberg@google.com>
---
 refs.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/refs.c b/refs.c
index 9c813f9..3e98ca1 100644
--- a/refs.c
+++ b/refs.c
@@ -2574,8 +2574,10 @@ int repack_without_refs(const char **refnames, int n, struct strbuf *err)
 	/* Remove any other accumulated cruft */
 	do_for_each_entry_in_dir(packed, 0, curate_packed_ref_fn, &refs_to_delete);
 	for_each_string_list_item(ref_to_delete, &refs_to_delete) {
-		if (remove_entry(packed, ref_to_delete->string) == -1)
+		if (remove_entry(packed, ref_to_delete->string) == -1) {
+			rollback_packed_refs();
 			die("internal error");
+		}
 	}
 
 	/* Write what remains */
-- 
2.0.1.523.g0041e8a