From d396100278a96826a60c383e8cb84d755c43f50e Mon Sep 17 00:00:00 2001 From: Milan Broz Date: Wed, 20 May 2009 11:09:49 +0000 Subject: [PATCH] Use readahead of underlying device and not default (smaller) one. When we are stacking LV over device, which has for some reason increased read_ahead (e.g. MD RAID), the read_ahead hint for libdevmapper is wrong (it is zero). If the calculated read_ahead hint is zero, patch uses read_ahead of underlying device (if first segment is PV) when setting DM_READ_AHEAD_MINIMUM_FLAG. Because we are using dev-cache, it also store this value to cache for future use (if several LVs are over one PV, BLKRAGET is called only once for underlying device.) This should fix all the reamining problems with readahead mismatch reported for DM over MD configurations (and similar cases). --- WHATS_NEW | 1 + lib/activate/activate.c | 5 +++++ lib/activate/dev_manager.c | 2 ++ lib/device/dev-cache.c | 2 ++ lib/device/dev-io.c | 44 ++++++++++++++++++++++++++++++++++++++ lib/device/device.h | 2 ++ lib/metadata/metadata.c | 29 +++++++++++++++++++++++++ lib/metadata/metadata.h | 5 +++++ test/t-read-ahead.sh | 18 ++++++++++------ 9 files changed, 101 insertions(+), 7 deletions(-) diff --git a/WHATS_NEW b/WHATS_NEW index 0f1f6eb23..9a98105d2 100644 --- a/WHATS_NEW +++ b/WHATS_NEW @@ -1,5 +1,6 @@ Version 2.02.46 - ================================ + Inherit read ahead from underlying device. Use lock query instead of activate_lv_excl. Enable online resizing of mirrors. Use suspend with flush when device size was changed during table preload. diff --git a/lib/activate/activate.c b/lib/activate/activate.c index 01df64383..9619f7adc 100644 --- a/lib/activate/activate.c +++ b/lib/activate/activate.c @@ -469,6 +469,11 @@ static int _lv_info(struct cmd_context *cmd, const struct logical_volume *lv, in info->live_table = dminfo.live_table; info->inactive_table = dminfo.inactive_table; + /* + * Cache read ahead value for PV devices now (before possible suspend) + */ + (void)lv_calculate_readhead(lv); + if (name) dm_pool_free(cmd->mem, name); diff --git a/lib/activate/dev_manager.c b/lib/activate/dev_manager.c index 0b227306f..80b7bd4ea 100644 --- a/lib/activate/dev_manager.c +++ b/lib/activate/dev_manager.c @@ -1022,6 +1022,8 @@ static int _add_new_lv_to_dtree(struct dev_manager *dm, struct dm_tree *dtree, if (read_ahead == DM_READ_AHEAD_AUTO) { /* we need RA at least twice a whole stripe - see the comment in md/raid0.c */ read_ahead = max_stripe_size * 2; + if (!read_ahead) + read_ahead = lv_calculate_readhead(lv); read_ahead_flags = DM_READ_AHEAD_MINIMUM_FLAG; } diff --git a/lib/device/dev-cache.c b/lib/device/dev-cache.c index d3c58fcd0..dd4ce6a8e 100644 --- a/lib/device/dev-cache.c +++ b/lib/device/dev-cache.c @@ -104,6 +104,7 @@ struct device *dev_create_file(const char *filename, struct device *dev, dev->fd = -1; dev->open_count = 0; dev->block_size = -1; + dev->read_ahead = -1; memset(dev->pvid, 0, sizeof(dev->pvid)); dm_list_init(&dev->open_list); @@ -124,6 +125,7 @@ static struct device *_dev_create(dev_t d) dev->fd = -1; dev->open_count = 0; dev->block_size = -1; + dev->read_ahead = -1; dev->end = UINT64_C(0); memset(dev->pvid, 0, sizeof(dev->pvid)); dm_list_init(&dev->open_list); diff --git a/lib/device/dev-io.c b/lib/device/dev-io.c index c163d93cc..06675e22c 100644 --- a/lib/device/dev-io.c +++ b/lib/device/dev-io.c @@ -262,6 +262,37 @@ static int _dev_get_size_dev(const struct device *dev, uint64_t *size) return 1; } +static int _dev_read_ahead_dev(struct device *dev, uint32_t *read_ahead) +{ + long read_ahead_long; + + if (dev->read_ahead != -1) { + *read_ahead = (uint32_t) dev->read_ahead; + return 1; + } + + if (!dev_open(dev)) + return_0; + + if (ioctl(dev->fd, BLKRAGET, &read_ahead_long) < 0) { + log_sys_error("ioctl BLKRAGET", dev_name(dev)); + if (!dev_close(dev)) + stack; + return 0; + } + + if (!dev_close(dev)) + stack; + + *read_ahead = (uint32_t) read_ahead_long; + dev->read_ahead = read_ahead_long; + + log_very_verbose("%s: read_ahead is %u sectors", + dev_name(dev), *read_ahead); + + return 1; +} + /*----------------------------------------------------------------- * Public functions *---------------------------------------------------------------*/ @@ -277,6 +308,19 @@ int dev_get_size(const struct device *dev, uint64_t *size) return _dev_get_size_dev(dev, size); } +int dev_get_read_ahead(struct device *dev, uint32_t *read_ahead) +{ + if (!dev) + return 0; + + if (dev->flags & DEV_REGULAR) { + *read_ahead = 0; + return 1; + } + + return _dev_read_ahead_dev(dev, read_ahead); +} + /* FIXME Unused int dev_get_sectsize(struct device *dev, uint32_t *size) { diff --git a/lib/device/device.h b/lib/device/device.h index abec65025..94f17b43e 100644 --- a/lib/device/device.h +++ b/lib/device/device.h @@ -40,6 +40,7 @@ struct device { int fd; int open_count; int block_size; + int read_ahead; uint32_t flags; uint64_t end; struct dm_list open_list; @@ -64,6 +65,7 @@ struct device_area { */ int dev_get_size(const struct device *dev, uint64_t *size); int dev_get_sectsize(struct device *dev, uint32_t *size); +int dev_get_read_ahead(struct device *dev, uint32_t *read_ahead); /* Use quiet version if device number could change e.g. when opening LV */ int dev_open(struct device *dev); diff --git a/lib/metadata/metadata.c b/lib/metadata/metadata.c index f4e4fde1e..d71a4fafe 100644 --- a/lib/metadata/metadata.c +++ b/lib/metadata/metadata.c @@ -1414,6 +1414,35 @@ static int _vg_mark_partial_lvs(struct volume_group *vg) return 1; } +/* + * Be sure that all PV devices have cached read ahead in dev-cache + * Currently it takes read_ahead from first PV segment only + */ +static int _lv_read_ahead_single(struct logical_volume *lv, void *data) +{ + struct lv_segment *seg = first_seg(lv); + uint32_t seg_read_ahead = 0, *read_ahead = data; + + if (seg && seg_type(seg, 0) == AREA_PV) + dev_get_read_ahead(seg_pv(seg, 0)->dev, &seg_read_ahead); + + if (seg_read_ahead > *read_ahead) + *read_ahead = seg_read_ahead; + + return 1; +} + +uint32_t lv_calculate_readhead(const struct logical_volume *lv) +{ + uint32_t read_ahead = 0; + + if (lv->read_ahead == DM_READ_AHEAD_AUTO) + _lv_postorder((struct logical_volume *)lv, _lv_read_ahead_single, &read_ahead); + + log_debug("Calculated readahead of LV %s is %u", lv->name, read_ahead); + return read_ahead; +} + int vg_validate(struct volume_group *vg) { struct pv_list *pvl, *pvl2; diff --git a/lib/metadata/metadata.h b/lib/metadata/metadata.h index b2294bb14..380e6395d 100644 --- a/lib/metadata/metadata.h +++ b/lib/metadata/metadata.h @@ -344,6 +344,11 @@ struct lv_segment *get_only_segment_using_this_lv(struct logical_volume *lv); */ unsigned snapshot_count(const struct volume_group *vg); +/* + * Calculate readahead from underlying PV devices + */ +uint32_t lv_calculate_readhead(const struct logical_volume *lv); + /* * For internal metadata caching. */ diff --git a/test/t-read-ahead.sh b/test/t-read-ahead.sh index e11b81341..aab9a5067 100755 --- a/test/t-read-ahead.sh +++ b/test/t-read-ahead.sh @@ -32,17 +32,21 @@ check_lvs_() { aux prepare_vg 5 #COMM "test various read ahead settings (bz450922)" -lvcreate -n "$lv" -l 100%FREE -i5 -I256 "$vg" +lvcreate -n "$lv" -l 100%FREE -i5 -I256 "$vg" ra="$(get_lvs_ lv_kernel_read_ahead)" test "$(( ( $ra / 5 ) * 5 ))" -eq $ra -lvdisplay "$vg"/"$lv" -lvchange -r auto "$vg"/"$lv" 2>&1 | grep auto -check_lvs_ lv_read_ahead auto -check_lvs_ lv_kernel_read_ahead 5120 -lvchange -r 400 "$vg/$lv" -check_lvs_ lv_read_ahead 400 +lvdisplay "$vg"/"$lv" +lvchange -r auto "$vg"/"$lv" 2>&1 | grep auto +check_lvs_ lv_read_ahead auto +check_lvs_ lv_kernel_read_ahead 5120 +lvchange -r 400 "$vg/$lv" +check_lvs_ lv_read_ahead 400 lvremove -ff "$vg" +#COMM "read ahead is properly inherited from underlying PV" +blockdev --setra 768 $dev1 +lvcreate -n $lv -L4M $vg $dev1 +test $(blockdev --getra $G_dev_/$vg/$lv) -eq 768 # Check default, active/inactive values for read_ahead / kernel_read_ahead lvcreate -n $lv -l 50%FREE $vg lvchange -an $vg/$lv