[lvm-devel] master - io: use sync io if aio fails
David Teigland
teigland at sourceware.org
Tue Nov 20 15:25:09 UTC 2018
Gitweb: https://sourceware.org/git/?p=lvm2.git;a=commitdiff;h=ca66d520326493311a3c7132b1bcee0807862301
Commit: ca66d520326493311a3c7132b1bcee0807862301
Parent: b1e9fe9505293e8c9b4a4bfffafe62c5a83b4d11
Author: David Teigland <teigland at redhat.com>
AuthorDate: Fri Nov 16 12:21:20 2018 -0600
Committer: David Teigland <teigland at redhat.com>
CommitterDate: Tue Nov 20 09:13:20 2018 -0600
io: use sync io if aio fails
io_setup() for aio may fail if a system has reached the
aio request limit. In this case, fall back to using
sync io. Also, lvm use of aio can be disabled entirely
with config setting global/use_aio=0.
The system limit for aio requests can be seen from
/proc/sys/fs/aio-max-nr
The current usage of aio requests can be seen from
/proc/sys/fs/aio-nr
The system limit for aio requests can be increased by
setting fs.aio-max-nr using sysctl.
Also add last-byte limit to the sync io code.
---
lib/commands/toolcontext.c | 2 ++
lib/config/config_settings.h | 3 +++
lib/config/defaults.h | 1 +
lib/device/bcache.c | 42 ++++++++++++++++++++++++++++++++++++++++++
lib/label/label.c | 17 +++++++++++++----
lib/misc/lvm-globals.c | 11 +++++++++++
lib/misc/lvm-globals.h | 2 ++
7 files changed, 74 insertions(+), 4 deletions(-)
diff --git a/lib/commands/toolcontext.c b/lib/commands/toolcontext.c
index 58d46ac..754be86 100644
--- a/lib/commands/toolcontext.c
+++ b/lib/commands/toolcontext.c
@@ -331,6 +331,8 @@ static void _init_logging(struct cmd_context *cmd)
find_config_tree_bool(cmd, global_test_CFG, NULL);
init_test(cmd->default_settings.test);
+ init_use_aio(find_config_tree_bool(cmd, global_use_aio_CFG, NULL));
+
/* Settings for logging to file */
if (find_config_tree_bool(cmd, log_overwrite_CFG, NULL))
append = 0;
diff --git a/lib/config/config_settings.h b/lib/config/config_settings.h
index 636446f..29ec980 100644
--- a/lib/config/config_settings.h
+++ b/lib/config/config_settings.h
@@ -1003,6 +1003,9 @@ cfg(global_use_lvmetad_CFG, "use_lvmetad", global_CFG_SECTION, 0, CFG_TYPE_BOOL,
cfg(global_lvmetad_update_wait_time_CFG, "lvmetad_update_wait_time", global_CFG_SECTION, CFG_DEFAULT_COMMENTED, CFG_TYPE_INT, 0, vsn(2, 2, 151), NULL, vsn(3, 0, 0), NULL,
"This setting is no longer used.\n")
+cfg(global_use_aio_CFG, "use_aio", global_CFG_SECTION, CFG_DEFAULT_COMMENTED, CFG_TYPE_BOOL, DEFAULT_USE_AIO, vsn(2, 2, 183), NULL, 0, NULL,
+ "Use async I/O when reading and writing devices.\n")
+
cfg(global_use_lvmlockd_CFG, "use_lvmlockd", global_CFG_SECTION, 0, CFG_TYPE_BOOL, 0, vsn(2, 2, 124), NULL, 0, NULL,
"Use lvmlockd for locking among hosts using LVM on shared storage.\n"
"Applicable only if LVM is compiled with lockd support in which\n"
diff --git a/lib/config/defaults.h b/lib/config/defaults.h
index 9fbe8c2..f3fcb09 100644
--- a/lib/config/defaults.h
+++ b/lib/config/defaults.h
@@ -60,6 +60,7 @@
#define DEFAULT_METADATA_READ_ONLY 0
#define DEFAULT_LVDISPLAY_SHOWS_FULL_DEVICE_PATH 0
#define DEFAULT_UNKNOWN_DEVICE_NAME "[unknown]"
+#define DEFAULT_USE_AIO 1
#define DEFAULT_SANLOCK_LV_EXTEND_MB 256
diff --git a/lib/device/bcache.c b/lib/device/bcache.c
index 62970ef..7e640a4 100644
--- a/lib/device/bcache.c
+++ b/lib/device/bcache.c
@@ -389,6 +389,48 @@ static bool _sync_issue(struct io_engine *ioe, enum dir d, int fd,
return false;
}
+ /*
+ * If bcache block goes past where lvm wants to write, then clamp it.
+ */
+ if ((d == DIR_WRITE) && _last_byte_offset && (fd == _last_byte_fd)) {
+ uint64_t offset = where;
+ uint64_t nbytes = len;
+ sector_t limit_nbytes = 0;
+ sector_t extra_nbytes = 0;
+
+ if (offset > _last_byte_offset) {
+ log_error("Limit write at %llu len %llu beyond last byte %llu",
+ (unsigned long long)offset,
+ (unsigned long long)nbytes,
+ (unsigned long long)_last_byte_offset);
+ return false;
+ }
+
+ if (offset + nbytes > _last_byte_offset) {
+ limit_nbytes = _last_byte_offset - offset;
+ if (limit_nbytes % _last_byte_sector_size)
+ extra_nbytes = _last_byte_sector_size - (limit_nbytes % _last_byte_sector_size);
+
+ if (extra_nbytes) {
+ log_debug("Limit write at %llu len %llu to len %llu rounded to %llu",
+ (unsigned long long)offset,
+ (unsigned long long)nbytes,
+ (unsigned long long)limit_nbytes,
+ (unsigned long long)(limit_nbytes + extra_nbytes));
+ nbytes = limit_nbytes + extra_nbytes;
+ } else {
+ log_debug("Limit write at %llu len %llu to len %llu",
+ (unsigned long long)offset,
+ (unsigned long long)nbytes,
+ (unsigned long long)limit_nbytes);
+ nbytes = limit_nbytes;
+ }
+ }
+
+ where = offset;
+ len = nbytes;
+ }
+
while (len) {
do {
if (d == DIR_READ)
diff --git a/lib/label/label.c b/lib/label/label.c
index 5387161..82ebd71 100644
--- a/lib/label/label.c
+++ b/lib/label/label.c
@@ -799,7 +799,7 @@ out:
static int _setup_bcache(int cache_blocks)
{
- struct io_engine *ioe;
+ struct io_engine *ioe = NULL;
if (cache_blocks < MIN_BCACHE_BLOCKS)
cache_blocks = MIN_BCACHE_BLOCKS;
@@ -807,9 +807,18 @@ static int _setup_bcache(int cache_blocks)
if (cache_blocks > MAX_BCACHE_BLOCKS)
cache_blocks = MAX_BCACHE_BLOCKS;
- if (!(ioe = create_async_io_engine())) {
- log_error("Failed to create bcache io engine.");
- return 0;
+ if (use_aio()) {
+ if (!(ioe = create_async_io_engine())) {
+ log_warn("Failed to set up async io, using sync io.");
+ init_use_aio(0);
+ }
+ }
+
+ if (!ioe) {
+ if (!(ioe = create_sync_io_engine())) {
+ log_error("Failed to set up sync io.");
+ return 0;
+ }
}
if (!(scan_bcache = bcache_create(BCACHE_BLOCK_SIZE_IN_SECTORS, cache_blocks, ioe))) {
diff --git a/lib/misc/lvm-globals.c b/lib/misc/lvm-globals.c
index 86e6cf4..0ad60fd 100644
--- a/lib/misc/lvm-globals.c
+++ b/lib/misc/lvm-globals.c
@@ -24,6 +24,7 @@
static int _verbose_level = VERBOSE_BASE_LEVEL;
static int _silent = 0;
static int _test = 0;
+static int _use_aio = 0;
static int _md_filtering = 0;
static int _internal_filtering = 0;
static int _fwraid_filtering = 0;
@@ -69,6 +70,11 @@ void init_test(int level)
_test = level;
}
+void init_use_aio(int use_aio)
+{
+ _use_aio = use_aio;
+}
+
void init_md_filtering(int level)
{
_md_filtering = level;
@@ -215,6 +221,11 @@ int test_mode(void)
return _test;
}
+int use_aio(void)
+{
+ return _use_aio;
+}
+
int md_filtering(void)
{
return _md_filtering;
diff --git a/lib/misc/lvm-globals.h b/lib/misc/lvm-globals.h
index 6fc26cc..42dcc34 100644
--- a/lib/misc/lvm-globals.h
+++ b/lib/misc/lvm-globals.h
@@ -25,6 +25,7 @@ enum dev_ext_e;
void init_verbose(int level);
void init_silent(int silent);
void init_test(int level);
+void init_use_aio(int use_aio);
void init_md_filtering(int level);
void init_internal_filtering(int level);
void init_fwraid_filtering(int level);
@@ -55,6 +56,7 @@ const char *get_cmd_name(void);
void set_sysfs_dir_path(const char *path);
int test_mode(void);
+int use_aio(void);
int md_filtering(void);
int internal_filtering(void);
int fwraid_filtering(void);
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