[lvm-devel] 2018-06-01-stable - io: use sync io if aio fails
David Teigland
teigland at sourceware.org
Tue Nov 20 15:05:44 UTC 2018
Gitweb: https://sourceware.org/git/?p=lvm2.git;a=commitdiff;h=f8ce9bf3bc38df8f89021517d7967d94ace129df
Commit: f8ce9bf3bc38df8f89021517d7967d94ace129df
Parent: 9fda169077d09e4136d9af14990fb5bee045f196
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 09:00:26 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 c9596e2..ecd8fd7 100644
--- a/lib/commands/toolcontext.c
+++ b/lib/commands/toolcontext.c
@@ -333,6 +333,8 @@ 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 f49709c..3433d0c 100644
--- a/lib/config/config_settings.h
+++ b/lib/config/config_settings.h
@@ -935,6 +935,9 @@ cfg(global_lvdisplay_shows_full_device_path_CFG, "lvdisplay_shows_full_device_pa
"Previously this was always shown as /dev/vgname/lvname even when that\n"
"was never a valid path in the /dev filesystem.\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_lvmetad_CFG, "use_lvmetad", global_CFG_SECTION, 0, CFG_TYPE_BOOL, DEFAULT_USE_LVMETAD, vsn(2, 2, 93), "@DEFAULT_USE_LVMETAD@", 0, NULL,
"Use lvmetad to cache metadata and reduce disk scanning.\n"
"When enabled (and running), lvmetad provides LVM commands with VG\n"
diff --git a/lib/config/defaults.h b/lib/config/defaults.h
index 7cebd84..fc2f603 100644
--- a/lib/config/defaults.h
+++ b/lib/config/defaults.h
@@ -59,6 +59,7 @@
#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 6235256..571ee7a 100644
--- a/lib/device/bcache.c
+++ b/lib/device/bcache.c
@@ -388,6 +388,48 @@ 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 5377847..b26ff33 100644
--- a/lib/label/label.c
+++ b/lib/label/label.c
@@ -798,7 +798,7 @@ 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;
@@ -806,9 +806,18 @@ 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 9941489..82c5706 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;
@@ -71,6 +72,11 @@ 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;
@@ -227,6 +233,11 @@ 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 b383891..f985cfa 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);
@@ -58,6 +59,7 @@ 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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