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From: "Torsten Bögershausen" <tboegi@web.de>
To: Michael Haggerty <mhagger@alum.mit.edu>,
	Junio C Hamano <gitster@pobox.com>
Cc: git@vger.kernel.org, "Johannes Sixt" <j.sixt@viscovery.net>,
	"Jeff King" <peff@peff.net>,
	"Torsten Bögershausen" <tboegi@web.de>,
	"Eric Sunshine" <sunshine@sunshineco.com>
Subject: Re: [PATCH v3 00/25] Lockfile correctness and refactoring
Date: Tue, 15 Apr 2014 20:40:46 +0200	[thread overview]
Message-ID: <534D7D2E.7060100@web.de> (raw)
In-Reply-To: <1397483695-10888-1-git-send-email-mhagger@alum.mit.edu>

refs.c:
int close_ref(struct ref_lock *lock)
{
	if (close_lock_file(lock->lk))
		return -1;
	lock->lock_fd = -1;
	return 0;
}

When the close() fails, fd is still >= 0, even if the file is closed.

Could it be written like this ?

int close_ref(struct ref_lock *lock)
{
	return close_lock_file(lock->lk);
}
=====================
lockfile.c, line 49
 *   - filename holds the filename of the lockfile

I think we have a strbuf here? (which is a good thing),
should we write:
 *   - strbuf filename holds the filename of the lockfile
----------
(and at some places filename[0] is mentioned,
should that be filename.buf[0] ?)



=========================
int commit_lock_file(struct lock_file *lk)
{
	static struct strbuf result_file = STRBUF_INIT;
	int err;

	if (lk->fd >= 0 && close_lock_file(lk))
		return -1;
##What happens if close() fails and close_lock_file() returns != 0?
##Is the lk now in a good shaped state?
I think the file which had been open by lk->fd is in an unkown state,
and should not be used for anything.
When I remember it right, an error on close() can mean "the file could not
be written and closed as expected, it can be truncated or corrupted.
This can happen on a network file system like NFS, or probably even other FS.
For me the failing of close() means I smell a need for a rollback.

	if (!lk->active)
		die("BUG: attempt to commit unlocked object");

	/* remove ".lock": */
	strbuf_add(&result_file, lk->filename.buf,
		   lk->filename.len - LOCK_SUFFIX_LEN);
	err = rename(lk->filename.buf, result_file.buf);
	strbuf_reset(&result_file);
	if (err)
		return -1;
	lk->active = 0;
	strbuf_reset(&lk->filename);
	return 0;
}

================
Please treat my comments more than questions rather than answers,
thanks for an interesting reading

  parent reply	other threads:[~2014-04-15 18:44 UTC|newest]

Thread overview: 32+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-04-14 13:54 [PATCH v3 00/25] Lockfile correctness and refactoring Michael Haggerty
2014-04-14 13:54 ` [PATCH v3 01/25] unable_to_lock_die(): rename function from unable_to_lock_index_die() Michael Haggerty
2014-04-14 13:54 ` [PATCH v3 02/25] api-lockfile: expand the documentation Michael Haggerty
2014-04-14 13:54 ` [PATCH v3 03/25] rollback_lock_file(): do not clear filename redundantly Michael Haggerty
2014-04-14 13:54 ` [PATCH v3 04/25] rollback_lock_file(): set fd to -1 Michael Haggerty
2014-04-14 13:54 ` [PATCH v3 05/25] lockfile: unlock file if lockfile permissions cannot be adjusted Michael Haggerty
2014-04-14 13:54 ` [PATCH v3 06/25] hold_lock_file_for_append(): release lock on errors Michael Haggerty
2014-04-14 13:54 ` [PATCH v3 07/25] lock_file(): always add lock_file object to lock_file_list Michael Haggerty
2014-04-14 13:54 ` [PATCH v3 08/25] lockfile.c: document the various states of lock_file objects Michael Haggerty
2014-04-14 13:54 ` [PATCH v3 09/25] cache.h: define constants LOCK_SUFFIX and LOCK_SUFFIX_LEN Michael Haggerty
2014-04-14 13:54 ` [PATCH v3 10/25] delete_ref_loose(): don't muck around in the lock_file's filename Michael Haggerty
2014-04-14 13:54 ` [PATCH v3 11/25] prepare_index(): declare return value to be (const char *) Michael Haggerty
2014-04-14 13:54 ` [PATCH v3 12/25] write_packed_entry_fn(): convert cb_data into a (const int *) Michael Haggerty
2014-04-14 13:54 ` [PATCH v3 13/25] lock_file(): exit early if lockfile cannot be opened Michael Haggerty
2014-04-14 13:54 ` [PATCH v3 14/25] remove_lock_file(): call rollback_lock_file() Michael Haggerty
2014-04-14 13:54 ` [PATCH v3 15/25] commit_lock_file(): inline temporary variable Michael Haggerty
2014-04-14 13:54 ` [PATCH v3 16/25] commit_lock_file(): die() if called for unlocked lockfile object Michael Haggerty
2014-04-15  6:49   ` Johannes Sixt
2014-04-16 15:17     ` Michael Haggerty
2014-04-14 13:54 ` [PATCH v3 17/25] lockfile: avoid transitory invalid states Michael Haggerty
2014-04-14 13:54 ` [PATCH v3 18/25] struct lock_file: declare some fields volatile Michael Haggerty
2014-04-15  6:55   ` Johannes Sixt
2014-04-16 15:36     ` Michael Haggerty
2014-04-14 13:54 ` [PATCH v3 19/25] try_merge_strategy(): remove redundant lock_file allocation Michael Haggerty
2014-04-14 13:54 ` [PATCH v3 20/25] try_merge_strategy(): use a statically-allocated lock_file object Michael Haggerty
2014-04-14 13:54 ` [PATCH v3 21/25] commit_lock_file(): use a strbuf to manage temporary space Michael Haggerty
2014-04-14 13:54 ` [PATCH v3 22/25] Change lock_file::filename into a strbuf Michael Haggerty
2014-04-14 13:54 ` [PATCH v3 23/25] resolve_symlink(): use a strbuf for internal scratch space Michael Haggerty
2014-04-14 13:54 ` [PATCH v3 24/25] resolve_symlink(): take a strbuf parameter Michael Haggerty
2014-04-14 13:54 ` [PATCH v3 25/25] trim_last_path_elm(): replace last_path_elm() Michael Haggerty
2014-04-15 18:40 ` Torsten Bögershausen [this message]
2014-04-16 19:50   ` [PATCH v3 00/25] Lockfile correctness and refactoring Michael Haggerty

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