From d20ce59b80fdbe132749b010c55ec6dea4c395e0 Mon Sep 17 00:00:00 2001 From: Peter Rajnoha Date: Thu, 9 Sep 2010 13:13:12 +0000 Subject: [PATCH] Add random suffix to archive file names to prevent races when being created. In certain configurations, we're not under a VG rw lock while trying to write a new archive file with VG metadata. A common example is using "vgs" while having the content of backup and archive directories empty. The code scans the content of these directories and tries to determine the final index that should be used in archive name. Since we're not under a lock, we can get into a race while choosing the index which could end up showing errors about not being able to rename to final archive name. Let's add random number suffix to these archive file names so we can avoid the race. --- WHATS_NEW | 1 + lib/format_text/archive.c | 7 +++++-- 2 files changed, 6 insertions(+), 2 deletions(-) diff --git a/WHATS_NEW b/WHATS_NEW index e55f7a7a7..5e9e8ae92 100644 --- a/WHATS_NEW +++ b/WHATS_NEW @@ -1,5 +1,6 @@ Version 2.02.74 - ================================== + Add random suffix to archive file names to prevent races when being created. Reinitialize archive and backup handling on toolcontext refresh. Fix opprobriously slow I/O to cluster mirrors created with --nosync. Make poll_mirror_progress report PROGRESS_CHECK_FAILED if LV is not a mirror. diff --git a/lib/format_text/archive.c b/lib/format_text/archive.c index 95ac49d64..bf16da573 100644 --- a/lib/format_text/archive.c +++ b/lib/format_text/archive.c @@ -226,7 +226,7 @@ int archive_vg(struct volume_group *vg, const char *dir, const char *desc, uint32_t retain_days, uint32_t min_archive) { - int i, fd, renamed = 0; + int i, fd, rnum, renamed = 0; uint32_t ix = 0; struct archive_file *last; FILE *fp = NULL; @@ -271,9 +271,12 @@ int archive_vg(struct volume_group *vg, ix = last->index + 1; } + rnum = rand_r(&vg->cmd->rand_seed); + for (i = 0; i < 10; i++) { if (dm_snprintf(archive_name, sizeof(archive_name), - "%s/%s_%05u.vg", dir, vg->name, ix) < 0) { + "%s/%s_%05u-%d.vg", + dir, vg->name, ix, rnum) < 0) { log_error("Archive file name too long."); return 0; }