maildir-sync.c revision 7c65a07e04f28f2a881d83989f85f9ad0e87a7b4
76b43e4417bab52e913da39b5f5bc2a130d3f149Timo Sirainen/* Copyright (c) 2004-2008 Dovecot authors, see the included COPYING file */
0c17af9d3f9323136a94e66605776ed4462a172dTimo Sirainen Here's a description of how we handle Maildir synchronization and
0c17af9d3f9323136a94e66605776ed4462a172dTimo Sirainen it's problems:
0c17af9d3f9323136a94e66605776ed4462a172dTimo Sirainen We want to be as efficient as we can. The most efficient way to
137ea7ca34005345aa2304a940149b7f3774d727Timo Sirainen check if changes have occurred is to stat() the new/ and cur/
0c17af9d3f9323136a94e66605776ed4462a172dTimo Sirainen directories and uidlist file - if their mtimes haven't changed,
0c17af9d3f9323136a94e66605776ed4462a172dTimo Sirainen there's no changes and we don't need to do anything.
0c17af9d3f9323136a94e66605776ed4462a172dTimo Sirainen Problem 1: Multiple changes can happen within a single second -
0c17af9d3f9323136a94e66605776ed4462a172dTimo Sirainen nothing guarantees that once we synced it, someone else didn't just
0c17af9d3f9323136a94e66605776ed4462a172dTimo Sirainen then make a modification. Such modifications wouldn't get noticed
137ea7ca34005345aa2304a940149b7f3774d727Timo Sirainen until a new modification occurred later.
0c17af9d3f9323136a94e66605776ed4462a172dTimo Sirainen Problem 2: Syncing cur/ directory is much more costly than syncing
0c17af9d3f9323136a94e66605776ed4462a172dTimo Sirainen new/. Moving mails from new/ to cur/ will always change mtime of
0c17af9d3f9323136a94e66605776ed4462a172dTimo Sirainen cur/ causing us to sync it as well.
0c17af9d3f9323136a94e66605776ed4462a172dTimo Sirainen Problem 3: We may not be able to move mail from new/ to cur/
0c17af9d3f9323136a94e66605776ed4462a172dTimo Sirainen because we're out of quota, or simply because we're accessing a
0c17af9d3f9323136a94e66605776ed4462a172dTimo Sirainen read-only mailbox.
0c17af9d3f9323136a94e66605776ed4462a172dTimo Sirainen MAILDIR_SYNC_SECS
0c17af9d3f9323136a94e66605776ed4462a172dTimo Sirainen -----------------
0c17af9d3f9323136a94e66605776ed4462a172dTimo Sirainen Several checks below use MAILDIR_SYNC_SECS, which should be maximum
0c17af9d3f9323136a94e66605776ed4462a172dTimo Sirainen clock drift between all computers accessing the maildir (eg. via
0c17af9d3f9323136a94e66605776ed4462a172dTimo Sirainen NFS), rounded up to next second. Our default is 1 second, since
0c17af9d3f9323136a94e66605776ed4462a172dTimo Sirainen everyone should be using NTP.
0c17af9d3f9323136a94e66605776ed4462a172dTimo Sirainen Note that setting it to 0 works only if there's only one computer
0c17af9d3f9323136a94e66605776ed4462a172dTimo Sirainen accessing the maildir. It's practically impossible to make two
0c17af9d3f9323136a94e66605776ed4462a172dTimo Sirainen clocks _exactly_ synchronized.
0c17af9d3f9323136a94e66605776ed4462a172dTimo Sirainen It might be possible to only use file server's clock by looking at
0c17af9d3f9323136a94e66605776ed4462a172dTimo Sirainen the atime field, but I don't know how well that would actually work.
0c17af9d3f9323136a94e66605776ed4462a172dTimo Sirainen cur directory
0c17af9d3f9323136a94e66605776ed4462a172dTimo Sirainen -------------
0c17af9d3f9323136a94e66605776ed4462a172dTimo Sirainen We have dirty_cur_time variable which is set to cur/ directory's
0c17af9d3f9323136a94e66605776ed4462a172dTimo Sirainen mtime when it's >= time() - MAILDIR_SYNC_SECS and we _think_ we have
0c17af9d3f9323136a94e66605776ed4462a172dTimo Sirainen synchronized the directory.
0c17af9d3f9323136a94e66605776ed4462a172dTimo Sirainen When dirty_cur_time is non-zero, we don't synchronize the cur/
0c17af9d3f9323136a94e66605776ed4462a172dTimo Sirainen directory until
0c17af9d3f9323136a94e66605776ed4462a172dTimo Sirainen a) cur/'s mtime changes
0c17af9d3f9323136a94e66605776ed4462a172dTimo Sirainen b) opening a mail fails with ENOENT
0c17af9d3f9323136a94e66605776ed4462a172dTimo Sirainen c) time() > dirty_cur_time + MAILDIR_SYNC_SECS
0c17af9d3f9323136a94e66605776ed4462a172dTimo Sirainen This allows us to modify the maildir multiple times without having
0c17af9d3f9323136a94e66605776ed4462a172dTimo Sirainen to sync it at every change. The sync will eventually be done to
0c17af9d3f9323136a94e66605776ed4462a172dTimo Sirainen make sure we didn't miss any external changes.
0c17af9d3f9323136a94e66605776ed4462a172dTimo Sirainen The dirty_cur_time is set when:
0c17af9d3f9323136a94e66605776ed4462a172dTimo Sirainen - we change message flags
0c17af9d3f9323136a94e66605776ed4462a172dTimo Sirainen - we expunge messages
0c17af9d3f9323136a94e66605776ed4462a172dTimo Sirainen - we move mail from new/ to cur/
0c17af9d3f9323136a94e66605776ed4462a172dTimo Sirainen - we sync cur/ directory and it's mtime is >= time() - MAILDIR_SYNC_SECS
0c17af9d3f9323136a94e66605776ed4462a172dTimo Sirainen It's unset when we do the final syncing, ie. when mtime is
0c17af9d3f9323136a94e66605776ed4462a172dTimo Sirainen older than time() - MAILDIR_SYNC_SECS.
0c17af9d3f9323136a94e66605776ed4462a172dTimo Sirainen new directory
0c17af9d3f9323136a94e66605776ed4462a172dTimo Sirainen -------------
0c17af9d3f9323136a94e66605776ed4462a172dTimo Sirainen If new/'s mtime is >= time() - MAILDIR_SYNC_SECS, always synchronize
0c17af9d3f9323136a94e66605776ed4462a172dTimo Sirainen it. dirty_cur_time-like feature might save us a few syncs, but
0c17af9d3f9323136a94e66605776ed4462a172dTimo Sirainen that might break a client which saves a mail in one connection and
0c17af9d3f9323136a94e66605776ed4462a172dTimo Sirainen tries to fetch it in another one. new/ directory is almost always
0c17af9d3f9323136a94e66605776ed4462a172dTimo Sirainen empty, so syncing it should be very fast anyway. Actually this can
0c17af9d3f9323136a94e66605776ed4462a172dTimo Sirainen still happen if we sync only new/ dir while another client is also
0c17af9d3f9323136a94e66605776ed4462a172dTimo Sirainen moving mails from it to cur/ - it takes us a while to see them.
0c17af9d3f9323136a94e66605776ed4462a172dTimo Sirainen That's pretty unlikely to happen however, and only way to fix it
0c17af9d3f9323136a94e66605776ed4462a172dTimo Sirainen would be to always synchronize cur/ after new/.
0c17af9d3f9323136a94e66605776ed4462a172dTimo Sirainen Normally we move all mails from new/ to cur/ whenever we sync it. If
0c17af9d3f9323136a94e66605776ed4462a172dTimo Sirainen it's not possible for some reason, we mark the mail with "probably
0c17af9d3f9323136a94e66605776ed4462a172dTimo Sirainen exists in new/ directory" flag.
0c17af9d3f9323136a94e66605776ed4462a172dTimo Sirainen If rename() still fails because of ENOSPC or EDQUOT, we still save
0c17af9d3f9323136a94e66605776ed4462a172dTimo Sirainen the flag changes in index with dirty-flag on. When moving the mail
0c17af9d3f9323136a94e66605776ed4462a172dTimo Sirainen to cur/ directory, or when we notice it's already moved there, we
0c17af9d3f9323136a94e66605776ed4462a172dTimo Sirainen apply the flag changes to the filename, rename it and remove the
0c17af9d3f9323136a94e66605776ed4462a172dTimo Sirainen dirty flag. If there's dirty flags, this should be tried every time
0c17af9d3f9323136a94e66605776ed4462a172dTimo Sirainen after expunge or when closing the mailbox.
0c17af9d3f9323136a94e66605776ed4462a172dTimo Sirainen This file contains UID <-> filename mappings. It's updated only when
0c17af9d3f9323136a94e66605776ed4462a172dTimo Sirainen new mail arrives, so it may contain filenames that have already been
0c17af9d3f9323136a94e66605776ed4462a172dTimo Sirainen deleted. Updating is done by getting uidlist.lock file, writing the
0c17af9d3f9323136a94e66605776ed4462a172dTimo Sirainen whole uidlist into it and rename()ing it over the old uidlist. This
0c17af9d3f9323136a94e66605776ed4462a172dTimo Sirainen means there's no need to lock the file for reading.
0c17af9d3f9323136a94e66605776ed4462a172dTimo Sirainen Whenever uidlist is rewritten, it's mtime must be larger than the old
0c17af9d3f9323136a94e66605776ed4462a172dTimo Sirainen one's. Use utime() before rename() if needed. Note that inode checking
0c17af9d3f9323136a94e66605776ed4462a172dTimo Sirainen wouldn't have been sufficient as inode numbers can be reused.
0c17af9d3f9323136a94e66605776ed4462a172dTimo Sirainen This file is usually read the first time you need to know filename for
0c17af9d3f9323136a94e66605776ed4462a172dTimo Sirainen given UID. After that it's not re-read unless new mails come that we
0c17af9d3f9323136a94e66605776ed4462a172dTimo Sirainen don't know about.
0c17af9d3f9323136a94e66605776ed4462a172dTimo Sirainen broken clients
0c17af9d3f9323136a94e66605776ed4462a172dTimo Sirainen --------------
0c17af9d3f9323136a94e66605776ed4462a172dTimo Sirainen Originally the middle identifier in Maildir filename was specified
0c17af9d3f9323136a94e66605776ed4462a172dTimo Sirainen only as <process id>_<delivery counter>. That however created a
0c17af9d3f9323136a94e66605776ed4462a172dTimo Sirainen problem with randomized PIDs which made it possible that the same
0c17af9d3f9323136a94e66605776ed4462a172dTimo Sirainen PID was reused within one second.
0c17af9d3f9323136a94e66605776ed4462a172dTimo Sirainen So if within one second a mail was delivered, MUA moved it to cur/
0c17af9d3f9323136a94e66605776ed4462a172dTimo Sirainen and another mail was delivered by a new process using same PID as
0c17af9d3f9323136a94e66605776ed4462a172dTimo Sirainen the first one, we likely ended up overwriting the first mail when
0c17af9d3f9323136a94e66605776ed4462a172dTimo Sirainen the second mail was moved over it.
0c17af9d3f9323136a94e66605776ed4462a172dTimo Sirainen Nowadays everyone should be giving a bit more specific identifier,
0c17af9d3f9323136a94e66605776ed4462a172dTimo Sirainen for example include microseconds in it which Dovecot does.
0c17af9d3f9323136a94e66605776ed4462a172dTimo Sirainen There's a simple way to prevent this from happening in some cases:
0c17af9d3f9323136a94e66605776ed4462a172dTimo Sirainen Don't move the mail from new/ to cur/ if it's mtime is >= time() -
0c17af9d3f9323136a94e66605776ed4462a172dTimo Sirainen MAILDIR_SYNC_SECS. The second delivery's link() call then fails
0c17af9d3f9323136a94e66605776ed4462a172dTimo Sirainen because the file is already in new/, and it will then use a
0c17af9d3f9323136a94e66605776ed4462a172dTimo Sirainen different filename. There's a few problems with this however:
0c17af9d3f9323136a94e66605776ed4462a172dTimo Sirainen - it requires extra stat() call which is unneeded extra I/O
0c17af9d3f9323136a94e66605776ed4462a172dTimo Sirainen - another MUA might still move the mail to cur/
0c17af9d3f9323136a94e66605776ed4462a172dTimo Sirainen - if first file's flags are modified by either Dovecot or another
0c17af9d3f9323136a94e66605776ed4462a172dTimo Sirainen MUA, it's moved to cur/ (you _could_ just do the dirty-flagging
0c17af9d3f9323136a94e66605776ed4462a172dTimo Sirainen but that'd be ugly)
0c17af9d3f9323136a94e66605776ed4462a172dTimo Sirainen Because this is useful only for very few people and it requires
0c17af9d3f9323136a94e66605776ed4462a172dTimo Sirainen extra I/O, I decided not to implement this. It should be however
0c17af9d3f9323136a94e66605776ed4462a172dTimo Sirainen quite easy to do since we need to be able to deal with files in new/
0c17af9d3f9323136a94e66605776ed4462a172dTimo Sirainen It's also possible to never accidentally overwrite a mail by using
0c17af9d3f9323136a94e66605776ed4462a172dTimo Sirainen link() + unlink() rather than rename(). This however isn't very
0c17af9d3f9323136a94e66605776ed4462a172dTimo Sirainen good idea as it introduces potential race conditions when multiple
0c17af9d3f9323136a94e66605776ed4462a172dTimo Sirainen clients are accessing the mailbox:
0c17af9d3f9323136a94e66605776ed4462a172dTimo Sirainen Trying to move the same mail from new/ to cur/ at the same time:
0c17af9d3f9323136a94e66605776ed4462a172dTimo Sirainen a) Client 1 uses slightly different filename than client 2,
0c17af9d3f9323136a94e66605776ed4462a172dTimo Sirainen for example one sets read-flag on but the other doesn't.
0c17af9d3f9323136a94e66605776ed4462a172dTimo Sirainen You have the same mail duplicated now.
0c17af9d3f9323136a94e66605776ed4462a172dTimo Sirainen b) Client 3 sees the mail between Client 1's and 2's link() calls
0c17af9d3f9323136a94e66605776ed4462a172dTimo Sirainen and changes it's flag. You have the same mail duplicated now.
0c17af9d3f9323136a94e66605776ed4462a172dTimo Sirainen And it gets worse when they're unlink()ing in cur/ directory:
0c17af9d3f9323136a94e66605776ed4462a172dTimo Sirainen c) Client 1 changes mails's flag and client 2 changes it back
0c17af9d3f9323136a94e66605776ed4462a172dTimo Sirainen between 1's link() and unlink(). The mail is now expunged.
0c17af9d3f9323136a94e66605776ed4462a172dTimo Sirainen d) If you try to deal with the duplicates by unlink()ing another
0c17af9d3f9323136a94e66605776ed4462a172dTimo Sirainen one of them, you might end up unlinking both of them.
0c17af9d3f9323136a94e66605776ed4462a172dTimo Sirainen So, what should we do then if we notice a duplicate? First of all,
0c17af9d3f9323136a94e66605776ed4462a172dTimo Sirainen it might not be a duplicate at all, readdir() might have just
0c17af9d3f9323136a94e66605776ed4462a172dTimo Sirainen returned it twice because it was just renamed. What we should do is
0c17af9d3f9323136a94e66605776ed4462a172dTimo Sirainen create a completely new base name for it and rename() it to that.
0c17af9d3f9323136a94e66605776ed4462a172dTimo Sirainen If the call fails with ENOENT, it only means that it wasn't a
0c17af9d3f9323136a94e66605776ed4462a172dTimo Sirainen duplicate after all.
b66a7b7ab0db2c9ad425912d3f21a36fcf76d876Timo Sirainen/* When rename()ing many files from new/ to cur/, it's possible that next
b66a7b7ab0db2c9ad425912d3f21a36fcf76d876Timo Sirainen readdir() skips some files. we don't of course wish to lose them, so we
b66a7b7ab0db2c9ad425912d3f21a36fcf76d876Timo Sirainen go and rescan the new/ directory again from beginning until no files are
b66a7b7ab0db2c9ad425912d3f21a36fcf76d876Timo Sirainen left. This value is just an optimization to avoid checking the directory
b66a7b7ab0db2c9ad425912d3f21a36fcf76d876Timo Sirainen twice unneededly. usually only NFS is the problem case. 1 is the safest
b66a7b7ab0db2c9ad425912d3f21a36fcf76d876Timo Sirainen bet here, but I guess 5 will do just fine too. */
cbf7138b49d32fce0645dc6523fbb42cc07cb2faTimo Sirainen/* This is mostly to avoid infinite looping when rename() destination already
cbf7138b49d32fce0645dc6523fbb42cc07cb2faTimo Sirainen exists as the hard link of the file itself. */
d4dcb9c30dba354cff7af6d303ecef7698194c55Timo Sirainen struct maildir_uidlist_sync_ctx *uidlist_sync_ctx;
1582b4d531679849bba299c17b6ec9402b7df67dTimo Sirainen struct maildir_index_sync_context *index_sync_ctx;
9c7e765845357342923e16351181091028e5930fTimo Sirainenvoid maildir_sync_notify(struct maildir_sync_context *ctx)
6bf1543bb7af03324c04e8f9ac8e430f395989aeTimo Sirainen /* we got here from maildir-save.c. it has no
6bf1543bb7af03324c04e8f9ac8e430f395989aeTimo Sirainen maildir_sync_context, */
b00787191c3c31bebb939c3d00f1fcdb67356c69Timo Sirainen if (now - ctx->last_touch > MAILDIR_LOCK_TOUCH_SECS && ctx->locked) {
44dc970b18c4e2d06f34cb908924152156e4a45bTimo Sirainen (void)maildir_uidlist_lock_touch(ctx->mbox->uidlist);
44dc970b18c4e2d06f34cb908924152156e4a45bTimo Sirainen if (now - ctx->last_notify > MAIL_STORAGE_STAYALIVE_SECS) {
44dc970b18c4e2d06f34cb908924152156e4a45bTimo Sirainen if (box->storage->callbacks->notify_ok != NULL) {
e30b748edcef3cf3352478bf21fa8f785bdc773aTimo Sirainenmaildir_sync_context_new(struct maildir_mailbox *mbox,
b5e6f6f27c1461f0f9f202615eeb738a645188c3Timo Sirainen ctx->new_dir = t_strconcat(mbox->path, "/new", NULL);
b5e6f6f27c1461f0f9f202615eeb738a645188c3Timo Sirainen ctx->cur_dir = t_strconcat(mbox->path, "/cur", NULL);
0cb2e8eb55e70f8ebe1e8349bdf49e4cbe5d8834Timo Sirainenstatic void maildir_sync_deinit(struct maildir_sync_context *ctx)
e05181d973025627ba08b631c12c07c3bbc99528Timo Sirainen (void)maildir_uidlist_sync_deinit(&ctx->uidlist_sync_ctx);
0b3662995e9fa0d0d857ec5350ce2b1ee6d3b94fTimo Sirainen (void)maildir_sync_index_finish(&ctx->index_sync_ctx,
4b43f50117630aa12b3cfd0cbd05ae22ba27fec1Timo Sirainenstatic int maildir_fix_duplicate(struct maildir_sync_context *ctx,
6925fd9cd70c30884406d50f1d85efb6561e776cTimo Sirainen fname1 = maildir_uidlist_sync_get_full_filename(ctx->uidlist_sync_ctx,
6925fd9cd70c30884406d50f1d85efb6561e776cTimo Sirainen if (stat(path1, &st1) < 0 || stat(path2, &st2) < 0) {
4b43f50117630aa12b3cfd0cbd05ae22ba27fec1Timo Sirainen /* most likely the files just don't exist anymore.
4b43f50117630aa12b3cfd0cbd05ae22ba27fec1Timo Sirainen don't really care about other errors much. */
cbf7138b49d32fce0645dc6523fbb42cc07cb2faTimo Sirainen /* Files are the same. this means either a race condition
992a9e2d6c6ee45d87089ac54267e0198a7802c3Timo Sirainen between stat() calls, or that the files were link()ed. */
6925fd9cd70c30884406d50f1d85efb6561e776cTimo Sirainen if (st1.st_nlink > 1 && st2.st_nlink == st1.st_nlink &&
6925fd9cd70c30884406d50f1d85efb6561e776cTimo Sirainen st1.st_ctime < ioloop_time - DUPE_LINKS_DELETE_SECS) {
992a9e2d6c6ee45d87089ac54267e0198a7802c3Timo Sirainen /* The file has hard links and it hasn't had any
992a9e2d6c6ee45d87089ac54267e0198a7802c3Timo Sirainen changes (such as renames) for a while, so this
992a9e2d6c6ee45d87089ac54267e0198a7802c3Timo Sirainen isn't a race condition.
992a9e2d6c6ee45d87089ac54267e0198a7802c3Timo Sirainen rename()ing one file on top of the other would fix
992a9e2d6c6ee45d87089ac54267e0198a7802c3Timo Sirainen this safely, except POSIX decided that rename()
992a9e2d6c6ee45d87089ac54267e0198a7802c3Timo Sirainen doesn't work that way. So we'll have unlink() one
992a9e2d6c6ee45d87089ac54267e0198a7802c3Timo Sirainen and hope that another process didn't just decide to
992a9e2d6c6ee45d87089ac54267e0198a7802c3Timo Sirainen unlink() the other (uidlist lock prevents this from
992a9e2d6c6ee45d87089ac54267e0198a7802c3Timo Sirainen happening) */
6925fd9cd70c30884406d50f1d85efb6561e776cTimo Sirainen new_path = t_strconcat(ctx->mbox->path, "/new/", new_fname, NULL);
6925fd9cd70c30884406d50f1d85efb6561e776cTimo Sirainen i_warning("Fixed a duplicate: %s -> %s", path2, new_fname);
6925fd9cd70c30884406d50f1d85efb6561e776cTimo Sirainen mail_storage_set_critical(&ctx->mbox->storage->storage,
c93cd163f9c1d4b0ca29f49cbfdbf474caeef5bfTimo Sirainen "Couldn't fix a duplicate: rename(%s, %s) failed: %m",
8e5fedd9ada47735be8ac0f8af2a66e8528bd776Timo Sirainenmaildir_stat(struct maildir_mailbox *mbox, const char *path, struct stat *st_r)
32ee977e189266744ef69ac4e832fd3111d6f949Timo Sirainen for (i = 0;; i++) {
32ee977e189266744ef69ac4e832fd3111d6f949Timo Sirainen if (errno != ENOENT || i == MAILDIR_DELETE_RETRY_COUNT)
32ee977e189266744ef69ac4e832fd3111d6f949Timo Sirainen /* try again */
8e5fedd9ada47735be8ac0f8af2a66e8528bd776Timo Sirainen mail_storage_set_critical(mbox->ibox.box.storage,
6ef7e31619edfaa17ed044b45861d106a86191efTimo Sirainenstatic int maildir_scan_dir(struct maildir_sync_context *ctx, bool new_dir)
ccc895c0358108d2304239063e940b7d75f364abTimo Sirainen struct mail_storage *storage = &ctx->mbox->storage->storage;
b60baf6af900a610b2b2ddd24a46f8311acc3386Timo Sirainen unsigned int i = 0, move_count = 0;
d61a5e0e4ff58d1aa613f0d51161e5bb0f092514Timo Sirainen bool move_new, check_touch, dir_changed = FALSE;
32ee977e189266744ef69ac4e832fd3111d6f949Timo Sirainen for (i = 0;; i++) {
32ee977e189266744ef69ac4e832fd3111d6f949Timo Sirainen if (errno != ENOENT || i == MAILDIR_DELETE_RETRY_COUNT) {
32ee977e189266744ef69ac4e832fd3111d6f949Timo Sirainen /* try again */
d61a5e0e4ff58d1aa613f0d51161e5bb0f092514Timo Sirainen ctx->mbox->maildir_hdr.new_mtime = st.st_mtime;
d61a5e0e4ff58d1aa613f0d51161e5bb0f092514Timo Sirainen ctx->mbox->maildir_hdr.new_mtime_nsecs = st.st_mtim.tv_nsec;
d77c309fccbc6a7594f8cb08fb01009fa613c568Timo Sirainen ctx->mbox->maildir_hdr.cur_mtime = st.st_mtime;
d77c309fccbc6a7594f8cb08fb01009fa613c568Timo Sirainen ctx->mbox->maildir_hdr.cur_mtime_nsecs = st.st_mtim.tv_nsec;
d3eff05aaa4c2bc0a7580ee87a54f6693f4a8241Timo Sirainen move_new = new_dir && !mailbox_is_readonly(&ctx->mbox->ibox.box) &&
0cb2e8eb55e70f8ebe1e8349bdf49e4cbe5d8834Timo Sirainen for (; (dp = readdir(dirp)) != NULL; errno = 0) {
b60baf6af900a610b2b2ddd24a46f8311acc3386Timo Sirainen str_printfa(src, "%s/%s", ctx->new_dir, dp->d_name);
641f0c0900ee6e7cf9667f4b40ed95cec7d0cdcaTimo Sirainen str_printfa(dest, "%s/%s", ctx->cur_dir, dp->d_name);
641f0c0900ee6e7cf9667f4b40ed95cec7d0cdcaTimo Sirainen if (strchr(dp->d_name, MAILDIR_INFO_SEP) == NULL) {
b60baf6af900a610b2b2ddd24a46f8311acc3386Timo Sirainen /* we moved it - it's \Recent for us */
1d3f7c1278168d5b1cbfa9a2cc9929a0909056b4Timo Sirainen /* someone else moved it already */
0cb2e8eb55e70f8ebe1e8349bdf49e4cbe5d8834Timo Sirainen } else if (ENOSPACE(errno) || errno == EACCES) {
0cb2e8eb55e70f8ebe1e8349bdf49e4cbe5d8834Timo Sirainen /* not enough disk space / read-only maildir,
0cb2e8eb55e70f8ebe1e8349bdf49e4cbe5d8834Timo Sirainen leave here */
0cb2e8eb55e70f8ebe1e8349bdf49e4cbe5d8834Timo Sirainen "rename(%s, %s) failed: %m",
b60baf6af900a610b2b2ddd24a46f8311acc3386Timo Sirainen if ((move_count % MAILDIR_SLOW_MOVE_COUNT) == 0)
d3eff05aaa4c2bc0a7580ee87a54f6693f4a8241Timo Sirainen } else if (new_dir) {
eddd9bf1a1369aea4a2715f6be1137da6d17d293Timo Sirainen ret = maildir_uidlist_sync_next(ctx->uidlist_sync_ctx,
0cb2e8eb55e70f8ebe1e8349bdf49e4cbe5d8834Timo Sirainen /* possibly duplicate - try fixing it */
d61a5e0e4ff58d1aa613f0d51161e5bb0f092514Timo Sirainen (move_count <= MAILDIR_RENAME_RESCAN_COUNT ? 0 : 1);
d61a5e0e4ff58d1aa613f0d51161e5bb0f092514Timo Sirainenint maildir_sync_header_refresh(struct maildir_mailbox *mbox)
d61a5e0e4ff58d1aa613f0d51161e5bb0f092514Timo Sirainen if (mail_index_refresh(mbox->ibox.index) < 0) {
7c65a07e04f28f2a881d83989f85f9ad0e87a7b4Timo Sirainen mail_index_get_header_ext(mbox->ibox.view, mbox->maildir_ext_id,
a3d22d3cb0e5436128ca7287cedc921f1789b2c8Timo Sirainen /* doesn't exist */
7c449f545b10daa47027552f98d916a9805da662Timo Sirainenstatic int maildir_sync_quick_check(struct maildir_mailbox *mbox, bool undirty,
d61a5e0e4ff58d1aa613f0d51161e5bb0f092514Timo Sirainen ((unsigned int)(st).st_mtim.tv_nsec != (hdr)->name ## _mtime_nsecs)
d61a5e0e4ff58d1aa613f0d51161e5bb0f092514Timo Sirainen (hdr)->name ## _mtime + MAILDIR_SYNC_SECS && \
d61a5e0e4ff58d1aa613f0d51161e5bb0f092514Timo Sirainen (time_t)(hdr)->name ## _check_time < ioloop_time - MAILDIR_SYNC_SECS))
d61a5e0e4ff58d1aa613f0d51161e5bb0f092514Timo Sirainen ((st).st_mtime != (time_t)(hdr)->name ## _mtime || \
0cb2e8eb55e70f8ebe1e8349bdf49e4cbe5d8834Timo Sirainen struct maildir_index_header *hdr = &mbox->maildir_hdr;
d61a5e0e4ff58d1aa613f0d51161e5bb0f092514Timo Sirainen bool refreshed = FALSE, check_new = FALSE, check_cur = FALSE;
d61a5e0e4ff58d1aa613f0d51161e5bb0f092514Timo Sirainen /* first sync */
0cb2e8eb55e70f8ebe1e8349bdf49e4cbe5d8834Timo Sirainen /* try to avoid stat()ing by first checking delayed changes */
bde6382cf65fba6165dc3603f5419e194d87f404Timo Sirainen /* refresh index and try again */
0cb2e8eb55e70f8ebe1e8349bdf49e4cbe5d8834Timo Sirainen *new_changed_r = DIR_MTIME_CHANGED(new_st, hdr, new);
7895c4845da515b0aa9bb156674a1fca40803f44Timo Sirainen *cur_changed_r = DIR_MTIME_CHANGED(cur_st, hdr, cur);
7895c4845da515b0aa9bb156674a1fca40803f44Timo Sirainen if ((!*new_changed_r && !*cur_changed_r) || refreshed)
7895c4845da515b0aa9bb156674a1fca40803f44Timo Sirainen /* refresh index and try again */
7895c4845da515b0aa9bb156674a1fca40803f44Timo Sirainenstatic void maildir_sync_update_next_uid(struct maildir_mailbox *mbox)
1d3f7c1278168d5b1cbfa9a2cc9929a0909056b4Timo Sirainen uid_validity = maildir_uidlist_get_uid_validity(mbox->uidlist);
1d3f7c1278168d5b1cbfa9a2cc9929a0909056b4Timo Sirainen next_uid = maildir_uidlist_get_next_uid(mbox->uidlist);
1d3f7c1278168d5b1cbfa9a2cc9929a0909056b4Timo Sirainen if (uid_validity == hdr->uid_validity || uid_validity == 0) {
1d3f7c1278168d5b1cbfa9a2cc9929a0909056b4Timo Sirainen /* make sure uidlist's next_uid is at least as large as
1d3f7c1278168d5b1cbfa9a2cc9929a0909056b4Timo Sirainen index file's. typically this happens only if uidlist gets
1d3f7c1278168d5b1cbfa9a2cc9929a0909056b4Timo Sirainen maildir_uidlist_set_uid_validity(mbox->uidlist,
1d3f7c1278168d5b1cbfa9a2cc9929a0909056b4Timo Sirainenstatic bool move_recent_messages(struct maildir_sync_context *ctx)
7c449f545b10daa47027552f98d916a9805da662Timo Sirainen (void)maildir_uidlist_refresh(ctx->mbox->uidlist);
c2cb5e469cd11759da22d82083d4fbb564d06dfaTimo Sirainen /* if there are files in new/, we'll need to move them. we'll check
c2cb5e469cd11759da22d82083d4fbb564d06dfaTimo Sirainen this by checking if we have any recent messages */
c2cb5e469cd11759da22d82083d4fbb564d06dfaTimo Sirainen hdr = mail_index_get_header(ctx->mbox->ibox.view);
c2cb5e469cd11759da22d82083d4fbb564d06dfaTimo Sirainen maildir_uidlist_get_next_uid(ctx->mbox->uidlist);
c2cb5e469cd11759da22d82083d4fbb564d06dfaTimo Sirainenstatic int maildir_sync_get_changes(struct maildir_sync_context *ctx,
c2cb5e469cd11759da22d82083d4fbb564d06dfaTimo Sirainen bool undirty = (ctx->flags & MAILBOX_SYNC_FLAG_FULL_READ) != 0;
c2cb5e469cd11759da22d82083d4fbb564d06dfaTimo Sirainen if (maildir_sync_quick_check(ctx->mbox, undirty,
c2cb5e469cd11759da22d82083d4fbb564d06dfaTimo Sirainen return mail_index_sync_have_any(ctx->mbox->ibox.index, flags) ? 1 : 0;
c2cb5e469cd11759da22d82083d4fbb564d06dfaTimo Sirainenstatic int maildir_sync_context(struct maildir_sync_context *ctx, bool forced,
d4dcb9c30dba354cff7af6d303ecef7698194c55Timo Sirainen ret = maildir_sync_get_changes(ctx, &new_changed, &cur_changed);
d4dcb9c30dba354cff7af6d303ecef7698194c55Timo Sirainen Locking, locking, locking.. Wasn't maildir supposed to be lockless?
d4dcb9c30dba354cff7af6d303ecef7698194c55Timo Sirainen We can get here either as beginning a real maildir sync, or when
d4dcb9c30dba354cff7af6d303ecef7698194c55Timo Sirainen committing changes to maildir but a file was lost (maybe renamed).
d4dcb9c30dba354cff7af6d303ecef7698194c55Timo Sirainen So, we're going to need two locks. One for index and one for
d4dcb9c30dba354cff7af6d303ecef7698194c55Timo Sirainen uidlist. To avoid deadlocking do the uidlist lock always first.
d4dcb9c30dba354cff7af6d303ecef7698194c55Timo Sirainen uidlist is needed only for figuring out UIDs for newly seen files,
d4dcb9c30dba354cff7af6d303ecef7698194c55Timo Sirainen so theoretically we wouldn't need to lock it unless there are new
d4dcb9c30dba354cff7af6d303ecef7698194c55Timo Sirainen files. It has a few problems though, assuming the index lock didn't
d4dcb9c30dba354cff7af6d303ecef7698194c55Timo Sirainen already protect it (eg. in-memory indexes):
d4dcb9c30dba354cff7af6d303ecef7698194c55Timo Sirainen 1. Just because you see a new file which doesn't exist in uidlist
d4dcb9c30dba354cff7af6d303ecef7698194c55Timo Sirainen file, doesn't mean that the file really exists anymore, or that
d4dcb9c30dba354cff7af6d303ecef7698194c55Timo Sirainen your readdir() lists all new files. Meaning that this is possible:
d4dcb9c30dba354cff7af6d303ecef7698194c55Timo Sirainen A: opendir(), readdir() -> new file ...
d4dcb9c30dba354cff7af6d303ecef7698194c55Timo Sirainen -- new files are written to the maildir --
d4dcb9c30dba354cff7af6d303ecef7698194c55Timo Sirainen B: opendir(), readdir() -> new file, lock uidlist,
d4dcb9c30dba354cff7af6d303ecef7698194c55Timo Sirainen readdir() -> another new file, rewrite uidlist, unlock
d4dcb9c30dba354cff7af6d303ecef7698194c55Timo Sirainen A: ... lock uidlist, readdir() -> nothing left, rewrite uidlist,
d4dcb9c30dba354cff7af6d303ecef7698194c55Timo Sirainen The second time running A didn't see the two new files. To handle
d4dcb9c30dba354cff7af6d303ecef7698194c55Timo Sirainen this correctly, it must not remove the new unseen files from
d4dcb9c30dba354cff7af6d303ecef7698194c55Timo Sirainen uidlist. This is possible to do, but adds extra complexity.
65d6ca3fb5450b81df0190d9e9aa62c00fed5116Timo Sirainen 2. If another process is rename()ing files while we are
f7ad1162969feff6b08f0e640a928db1783daae9Timo Sirainen readdir()ing, it's possible that readdir() never lists some files,
1582b4d531679849bba299c17b6ec9402b7df67dTimo Sirainen causing Dovecot to assume they were expunged. In next sync they
1582b4d531679849bba299c17b6ec9402b7df67dTimo Sirainen would show up again, but client could have already been notified of
1582b4d531679849bba299c17b6ec9402b7df67dTimo Sirainen that and they would show up under new UIDs, so the damage is
1582b4d531679849bba299c17b6ec9402b7df67dTimo Sirainen already done.
f7ad1162969feff6b08f0e640a928db1783daae9Timo Sirainen Both of the problems can be avoided if we simply lock the uidlist
f7ad1162969feff6b08f0e640a928db1783daae9Timo Sirainen before syncing and keep it until sync is finished. Typically this
e30b748edcef3cf3352478bf21fa8f785bdc773aTimo Sirainen would happen in any case, as there is the index lock..
1582b4d531679849bba299c17b6ec9402b7df67dTimo Sirainen The second case is still a problem with external changes though,
649823f9c7e42a424a8fadc427e12f3576c4f714Timo Sirainen because maildir doesn't require any kind of locking. Luckily this
57a91f930a12d2cd1220da4f3f7cb2c47557cd37Timo Sirainen problem rarely happens except under high amount of modifications.
ba3d9eeb0bec6ed8465d68fa2480ad085559b580Timo Sirainen if ((ctx->flags & MAILBOX_SYNC_FLAG_FAST) != 0)
ba3d9eeb0bec6ed8465d68fa2480ad085559b580Timo Sirainen ret = maildir_uidlist_sync_init(ctx->mbox->uidlist, sync_flags,
ba3d9eeb0bec6ed8465d68fa2480ad085559b580Timo Sirainen /* failure / timeout */
ba3d9eeb0bec6ed8465d68fa2480ad085559b580Timo Sirainen ctx->locked = maildir_uidlist_is_locked(ctx->mbox->uidlist);
ba3d9eeb0bec6ed8465d68fa2480ad085559b580Timo Sirainen if (!ctx->mbox->syncing_commit && ctx->locked) {
f7ad1162969feff6b08f0e640a928db1783daae9Timo Sirainen /* if we're going to check cur/ dir our current logic requires
73c76fa7340a107229c530196d026aadeae979c7Timo Sirainen that new/ dir is checked as well. it's a good idea anyway. */
ba3d9eeb0bec6ed8465d68fa2480ad085559b580Timo Sirainen unsigned int count = 0;
e05181d973025627ba08b631c12c07c3bbc99528Timo Sirainen while ((ret = maildir_scan_dir(ctx, TRUE)) > 0) {
e05181d973025627ba08b631c12c07c3bbc99528Timo Sirainen /* rename()d at least some files, which might have
e05181d973025627ba08b631c12c07c3bbc99528Timo Sirainen caused some other files to be missed. check again
e05181d973025627ba08b631c12c07c3bbc99528Timo Sirainen (see MAILDIR_RENAME_RESCAN_COUNT). */
b7b81543899e306c71e6152516d8698416162bcbTimo Sirainen /* finish uidlist syncing, but keep it still locked */
cce169a321c9c629e4f2db1a69dae3b75bbcb27aTimo Sirainen maildir_uidlist_sync_finish(ctx->uidlist_sync_ctx);
cce169a321c9c629e4f2db1a69dae3b75bbcb27aTimo Sirainen /* make sure we sync the maildir later */
cce169a321c9c629e4f2db1a69dae3b75bbcb27aTimo Sirainen if (!ctx->mbox->syncing_commit && ctx->locked) {
b7b81543899e306c71e6152516d8698416162bcbTimo Sirainen /* NOTE: index syncing here might cause a re-sync due to
0cb2e8eb55e70f8ebe1e8349bdf49e4cbe5d8834Timo Sirainen files getting lost, so this function might be called
7abd00c65bbf53fda3f638101c4cd43647d1eb07Timo Sirainen re-entrantly. */
7abd00c65bbf53fda3f638101c4cd43647d1eb07Timo Sirainen ret = maildir_sync_index(ctx->index_sync_ctx, ctx->partial);
7abd00c65bbf53fda3f638101c4cd43647d1eb07Timo Sirainen if (maildir_sync_index_finish(&ctx->index_sync_ctx,
e05181d973025627ba08b631c12c07c3bbc99528Timo Sirainen i_assert(maildir_uidlist_is_locked(ctx->mbox->uidlist));
e05181d973025627ba08b631c12c07c3bbc99528Timo Sirainen if (maildir_uidlist_lookup_nosync(ctx->mbox->uidlist, *find_uid,
4d938f46f4f956ecb802c30ca771922f5539a660Timo Sirainen /* UID is expunged */
cce169a321c9c629e4f2db1a69dae3b75bbcb27aTimo Sirainen } else if ((flags & MAILDIR_UIDLIST_REC_FLAG_NONSYNCED) == 0) {
ba3d9eeb0bec6ed8465d68fa2480ad085559b580Timo Sirainen /* we didn't find it, possibly expunged? */
fd1a173038402c968f82d6b19b8b2e029bbcee45Timo Sirainen return maildir_uidlist_sync_deinit(&ctx->uidlist_sync_ctx);
f7ad1162969feff6b08f0e640a928db1783daae9Timo Sirainenint maildir_storage_sync_force(struct maildir_mailbox *mbox, uint32_t uid)
c2cb5e469cd11759da22d82083d4fbb564d06dfaTimo Sirainen ctx = maildir_sync_context_new(mbox, MAILBOX_SYNC_FLAG_FAST);
0cb2e8eb55e70f8ebe1e8349bdf49e4cbe5d8834Timo Sirainen ret = maildir_sync_context(ctx, TRUE, &uid, &lost_files);
c2cb5e469cd11759da22d82083d4fbb564d06dfaTimo Sirainen /* maybe it's expunged. check again. */
eddd9bf1a1369aea4a2715f6be1137da6d17d293Timo Sirainenmaildir_storage_sync_init(struct mailbox *box, enum mailbox_sync_flags flags)
eddd9bf1a1369aea4a2715f6be1137da6d17d293Timo Sirainen struct maildir_mailbox *mbox = (struct maildir_mailbox *)box;
d756ebcfa96bd7cff02097c8f26df9df368b81b1Timo Sirainen if (index_mailbox_want_full_sync(&mbox->ibox, flags)) {
013e3b3942e9550fde619a0b3ce6bdd04edc4268Timo Sirainen i_assert(!maildir_uidlist_is_locked(mbox->uidlist) ||
eddd9bf1a1369aea4a2715f6be1137da6d17d293Timo Sirainen /* lost some files from new/, see if thery're in cur/ */
4d938f46f4f956ecb802c30ca771922f5539a660Timo Sirainen return index_mailbox_sync_init(box, flags, ret < 0);
cce169a321c9c629e4f2db1a69dae3b75bbcb27aTimo Sirainenint maildir_sync_is_synced(struct maildir_mailbox *mbox)
0cb2e8eb55e70f8ebe1e8349bdf49e4cbe5d8834Timo Sirainen new_dir = t_strconcat(mbox->path, "/new", NULL);
a3d22d3cb0e5436128ca7287cedc921f1789b2c8Timo Sirainen cur_dir = t_strconcat(mbox->path, "/cur", NULL);
a3d22d3cb0e5436128ca7287cedc921f1789b2c8Timo Sirainen ret = maildir_sync_quick_check(mbox, FALSE, new_dir, cur_dir,
a3d22d3cb0e5436128ca7287cedc921f1789b2c8Timo Sirainen return ret < 0 ? -1 : (!new_changed && !cur_changed);