From 3584e0c0d5e5992a3c93e03de8b6042de0853ef2 Mon Sep 17 00:00:00 2001 From: David Teigland Date: Mon, 4 Mar 2019 12:13:09 -0600 Subject: [PATCH] io: warn when metadata size approaches io memory size When a single copy of metadata gets within 1MB of the current io_memory_size value, begin printing a warning that the io_memory_size should be increased. --- lib/cache/lvmcache.c | 15 +++++++++++++ lib/cache/lvmcache.h | 3 +++ lib/format_text/format-text.c | 4 ++++ lib/label/label.c | 41 +++++++++++++++++++++++++++++++++++ 4 files changed, 63 insertions(+) diff --git a/lib/cache/lvmcache.c b/lib/cache/lvmcache.c index 0ffa604df..8aed59ba9 100644 --- a/lib/cache/lvmcache.c +++ b/lib/cache/lvmcache.c @@ -2286,6 +2286,21 @@ int lvmcache_scan_mismatch(struct cmd_context *cmd, const char *vgname, const ch return 1; } +static uint64_t _max_metadata_size; + +void lvmcache_save_metadata_size(uint64_t val) +{ + if (!_max_metadata_size) + _max_metadata_size = val; + else if (_max_metadata_size < val) + _max_metadata_size = val; +} + +uint64_t lvmcache_max_metadata_size(void) +{ + return _max_metadata_size; +} + int lvmcache_vginfo_has_pvid(struct lvmcache_vginfo *vginfo, char *pvid) { struct lvmcache_info *info; diff --git a/lib/cache/lvmcache.h b/lib/cache/lvmcache.h index 12f17dfa6..26e09535e 100644 --- a/lib/cache/lvmcache.h +++ b/lib/cache/lvmcache.h @@ -210,6 +210,9 @@ struct volume_group *lvmcache_get_saved_vg(const char *vgid, int precommitted); struct volume_group *lvmcache_get_saved_vg_latest(const char *vgid); void lvmcache_drop_saved_vgid(const char *vgid); +uint64_t lvmcache_max_metadata_size(void); +void lvmcache_save_metadata_size(uint64_t val); + int dev_in_device_list(struct device *dev, struct dm_list *head); #endif diff --git a/lib/format_text/format-text.c b/lib/format_text/format-text.c index 414941f22..d97617753 100644 --- a/lib/format_text/format-text.c +++ b/lib/format_text/format-text.c @@ -1548,6 +1548,10 @@ int read_metadata_location_summary(const struct format_type *fmt, */ vgsummary->mda_checksum = rlocn->checksum; vgsummary->mda_size = rlocn->size; + + /* Keep track of largest metadata size we find. */ + lvmcache_save_metadata_size(rlocn->size); + lvmcache_lookup_mda(vgsummary); if (!text_read_metadata_summary(fmt, dev_area->dev, MDA_CONTENT_REASON(primary_mda), diff --git a/lib/label/label.c b/lib/label/label.c index a877b388d..174139e55 100644 --- a/lib/label/label.c +++ b/lib/label/label.c @@ -23,6 +23,7 @@ #include "lib/commands/toolcontext.h" #include "lib/activate/activate.h" #include "lib/label/hints.h" +#include "lib/metadata/metadata.h" #include #include @@ -31,6 +32,8 @@ /* FIXME Allow for larger labels? Restricted to single sector currently */ +static uint64_t _current_bcache_size_bytes; + /* * Internal labeller struct. */ @@ -809,6 +812,8 @@ static int _setup_bcache(int num_devs) if (cache_blocks > MAX_BCACHE_BLOCKS) cache_blocks = MAX_BCACHE_BLOCKS; + _current_bcache_size_bytes = cache_blocks * BCACHE_BLOCK_SIZE_IN_SECTORS * 512; + if (use_aio()) { if (!(ioe = create_async_io_engine())) { log_warn("Failed to set up async io, using sync io."); @@ -854,6 +859,7 @@ int label_scan(struct cmd_context *cmd) struct dev_iter *iter; struct device_list *devl, *devl2; struct device *dev; + uint64_t max_metadata_size_bytes; int newhints = 0; log_debug_devs("Finding devices to scan"); @@ -934,6 +940,41 @@ int label_scan(struct cmd_context *cmd) */ _scan_list(cmd, cmd->filter, &scan_devs, NULL); + /* + * Metadata could be larger than total size of bcache, and bcache + * cannot currently be resized during the command. If this is the + * case (or within reach), warn that io_memory_size needs to be + * set larger. + * + * Even if bcache out of space did not cause a failure during scan, it + * may cause a failure during the next vg_read phase or during vg_write. + * + * If there was an error during scan, we could recreate bcache here + * with a larger size and then restart label_scan. But, this does not + * address the problem of writing new metadata that excedes the bcache + * size and failing, which would often be hit first, i.e. we'll fail + * to write new metadata exceding the max size before we have a chance + * to read any metadata with that size, unless we find an existing vg + * that has been previously created with the larger size. + * + * If the largest metadata is within 1MB of the bcache size, then start + * warning. + */ + max_metadata_size_bytes = lvmcache_max_metadata_size(); + + if (max_metadata_size_bytes + (1024 * 1024) > _current_bcache_size_bytes) { + /* we want bcache to be 1MB larger than the max metadata seen */ + uint64_t want_size_kb = (max_metadata_size_bytes / 1024) + 1024; + uint64_t remainder; + if ((remainder = (want_size_kb % 1024))) + want_size_kb = want_size_kb + 1024 - remainder; + + log_warn("WARNING: metadata may not be usable with current io_memory_size %d KiB", + io_memory_size()); + log_warn("WARNING: increase lvm.conf io_memory_size to at least %llu KiB", + (unsigned long long)want_size_kb); + } + dm_list_init(&cmd->hints); if (!dm_list_empty(&hints)) {