Date: Wed, 3 Apr 2019 17:04:38 +0000 (UTC) From: Kyle Evans <kevans@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r345848 - head/lib/libbe Message-ID: <201904031704.x33H4c0n056934@repo.freebsd.org>
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Author: kevans Date: Wed Apr 3 17:04:38 2019 New Revision: 345848 URL: https://svnweb.freebsd.org/changeset/base/345848 Log: libbe(3): Add a serial to the generated snapshot names To use bectl in an example, when one creates a new boot environment with either `bectl create <be>` or `bectl create -e <otherbe> <be>`, libbe will take a snapshot of the original boot environment to clone. Previously, this used %F-%T date format as the snapshot name, but this has some limitations- attempting to create multiple boot environments in quick succession may collide if done within the same second. Tack a serial onto it to reduce the chances of a collision... we could still collide if multiple processes/threads are creating boot environments at the same time, but this is likely not a big concern as this has only been reported as occurring in freebsd-ci setup. MFC after: 3 days Modified: head/lib/libbe/be.c Modified: head/lib/libbe/be.c ============================================================================== --- head/lib/libbe/be.c Wed Apr 3 17:02:18 2019 (r345847) +++ head/lib/libbe/be.c Wed Apr 3 17:04:38 2019 (r345848) @@ -56,6 +56,9 @@ static int be_create_child_noent(libbe_handle_t *lbh, static int be_create_child_cloned(libbe_handle_t *lbh, const char *active); #endif +/* Arbitrary... should tune */ +#define BE_SNAP_SERIAL_MAX 1024 + /* * Iterator function for locating the rootfs amongst the children of the * zfs_be_root set by loader(8). data is expected to be a libbe_handle_t *. @@ -320,13 +323,32 @@ be_destroy(libbe_handle_t *lbh, const char *name, int options & ~BE_DESTROY_ORIGIN)); } +static void +be_setup_snapshot_name(libbe_handle_t *lbh, char *buf, size_t buflen) +{ + time_t rawtime; + int len, serial; + + time(&rawtime); + len = strlen(buf); + len += strftime(buf + len, buflen - len, "@%F-%T", localtime(&rawtime)); + /* No room for serial... caller will do its best */ + if (buflen - len < 2) + return; + + for (serial = 0; serial < BE_SNAP_SERIAL_MAX; ++serial) { + snprintf(buf + len, buflen - len, "-%d", serial); + if (!zfs_dataset_exists(lbh->lzh, buf, ZFS_TYPE_SNAPSHOT)) + return; + } +} + int be_snapshot(libbe_handle_t *lbh, const char *source, const char *snap_name, bool recursive, char *result) { char buf[BE_MAXPATHLEN]; - time_t rawtime; - int len, err; + int err; be_root_concat(lbh, source, buf); @@ -344,10 +366,8 @@ be_snapshot(libbe_handle_t *lbh, const char *source, c snprintf(result, BE_MAXPATHLEN, "%s@%s", source, snap_name); } else { - time(&rawtime); - len = strlen(buf); - strftime(buf + len, sizeof(buf) - len, - "@%F-%T", localtime(&rawtime)); + be_setup_snapshot_name(lbh, buf, sizeof(buf)); + if (result != NULL && strlcpy(result, strrchr(buf, '/') + 1, sizeof(buf)) >= sizeof(buf)) return (set_error(lbh, BE_ERR_INVALIDNAME));
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