ext4: add prefetch_block_bitmaps mount options
For file systems where we can afford to keep the buddy bitmaps cached,
we can speed up initial writes to large file systems by starting to
load the block allocation bitmaps as soon as the file system is
mounted. This won't work well for _super_ large file systems, or
memory constrained systems, so we only enable this when it is
requested via a mount option.
Addresses-Google-Bug: 159488342
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Change-Id: Iad3356da63f624f5dc6345874c4ec9dda6dff51d
Reviewed-on: https://cos-review.googlesource.com/c/third_party/kernel/+/3303
Reviewed-by: Theodore Tso <tytso@google.com>
(cherry picked from commit b910e70ff4c899093b4677ed91c17447057d79f8)
This commit hasn't been merged upstream yet but has been reviewed
and will be available upstream soon.
BUG=b/159488342
TEST=Verified that the FS can be mounted with this mount option
SOURCE=UPSTREAM(3d392b2676bf3199863a1e5efb2c087ad9d442a4)
Change-Id: Iad3356da63f624f5dc6345874c4ec9dda6dff51d
Reviewed-on: https://cos-review.googlesource.com/c/third_party/kernel/+/4401
Reviewed-by: Theodore Tso <tytso@google.com>
Reviewed-by: Roy Yang <royyang@google.com>
diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index cca48e1..1d982cf 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -1153,6 +1153,7 @@
#define EXT4_MOUNT_JOURNAL_CHECKSUM 0x800000 /* Journal checksums */
#define EXT4_MOUNT_JOURNAL_ASYNC_COMMIT 0x1000000 /* Journal Async Commit */
#define EXT4_MOUNT_WARN_ON_ERROR 0x2000000 /* Trigger WARN_ON on error */
+#define EXT4_MOUNT_PREFETCH_BLOCK_BITMAPS 0x4000000
#define EXT4_MOUNT_DELALLOC 0x8000000 /* Delalloc support */
#define EXT4_MOUNT_DATA_ERR_ABORT 0x10000000 /* Abort on file data write */
#define EXT4_MOUNT_BLOCK_VALIDITY 0x20000000 /* Block validity checking */
@@ -2227,9 +2228,15 @@
struct mutex li_list_mtx;
};
+enum ext4_li_mode {
+ EXT4_LI_MODE_PREFETCH_BBITMAP,
+ EXT4_LI_MODE_ITABLE,
+};
+
struct ext4_li_request {
struct super_block *lr_super;
- struct ext4_sb_info *lr_sbi;
+ enum ext4_li_mode lr_mode;
+ ext4_group_t lr_first_not_zeroed;
ext4_group_t lr_next_group;
struct list_head lr_request;
unsigned long lr_next_sched;
@@ -2569,6 +2576,12 @@
extern void ext4_discard_preallocations(struct inode *);
extern int __init ext4_init_mballoc(void);
extern void ext4_exit_mballoc(void);
+extern ext4_group_t ext4_mb_prefetch(struct super_block *sb,
+ ext4_group_t group,
+ unsigned int nr, int *cnt);
+extern void ext4_mb_prefetch_fini(struct super_block *sb, ext4_group_t group,
+ unsigned int nr);
+
extern void ext4_free_blocks(handle_t *handle, struct inode *inode,
struct buffer_head *bh, ext4_fsblk_t block,
unsigned long count, int flags);
diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
index 2b51ae7..99b3b75 100644
--- a/fs/ext4/mballoc.c
+++ b/fs/ext4/mballoc.c
@@ -2121,9 +2121,8 @@
* Start prefetching @nr block bitmaps starting at @group.
* Return the next group which needs to be prefetched.
*/
-static ext4_group_t
-ext4_mb_prefetch(struct super_block *sb, ext4_group_t group,
- unsigned int nr, int *cnt)
+ext4_group_t ext4_mb_prefetch(struct super_block *sb, ext4_group_t group,
+ unsigned int nr, int *cnt)
{
ext4_group_t ngroups = ext4_get_groups_count(sb);
struct buffer_head *bh;
@@ -2173,9 +2172,8 @@
* waiting for the block allocation bitmap read to finish when
* ext4_mb_prefetch_fini is called from ext4_mb_regular_allocator().
*/
-static void
-ext4_mb_prefetch_fini(struct super_block *sb, ext4_group_t group,
- unsigned int nr)
+void ext4_mb_prefetch_fini(struct super_block *sb, ext4_group_t group,
+ unsigned int nr)
{
while (nr-- > 0) {
struct ext4_group_desc *gdp = ext4_get_group_desc(sb, group,
@@ -2197,7 +2195,6 @@
}
}
-
static noinline_for_stack int
ext4_mb_regular_allocator(struct ext4_allocation_context *ac)
{
diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 7dd1f79..3cb16c0 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -1470,6 +1470,7 @@
Opt_dioread_nolock, Opt_dioread_lock,
Opt_discard, Opt_nodiscard, Opt_init_itable, Opt_noinit_itable,
Opt_max_dir_size_kb, Opt_nojournal_checksum, Opt_nombcache,
+ Opt_prefetch_block_bitmaps,
};
static const match_table_t tokens = {
@@ -1556,6 +1557,7 @@
{Opt_test_dummy_encryption, "test_dummy_encryption"},
{Opt_nombcache, "nombcache"},
{Opt_nombcache, "no_mbcache"}, /* for backward compatibility */
+ {Opt_prefetch_block_bitmaps, "prefetch_block_bitmaps"},
{Opt_removed, "check=none"}, /* mount option from ext2/3 */
{Opt_removed, "nocheck"}, /* mount option from ext2/3 */
{Opt_removed, "reservation"}, /* mount option from ext2/3 */
@@ -1766,6 +1768,8 @@
{Opt_max_dir_size_kb, 0, MOPT_GTE0},
{Opt_test_dummy_encryption, 0, MOPT_GTE0},
{Opt_nombcache, EXT4_MOUNT_NO_MBCACHE, MOPT_SET},
+ {Opt_prefetch_block_bitmaps, EXT4_MOUNT_PREFETCH_BLOCK_BITMAPS,
+ MOPT_SET},
{Opt_err, 0, 0}
};
@@ -3050,15 +3054,34 @@
static int ext4_run_li_request(struct ext4_li_request *elr)
{
struct ext4_group_desc *gdp = NULL;
- ext4_group_t group, ngroups;
- struct super_block *sb;
+ struct super_block *sb = elr->lr_super;
+ ext4_group_t ngroups = EXT4_SB(sb)->s_groups_count;
+ ext4_group_t group = elr->lr_next_group;
unsigned long timeout = 0;
+ unsigned int prefetch_ios = 0;
int ret = 0;
- sb = elr->lr_super;
- ngroups = EXT4_SB(sb)->s_groups_count;
+ if (elr->lr_mode == EXT4_LI_MODE_PREFETCH_BBITMAP) {
+ elr->lr_next_group = ext4_mb_prefetch(sb, group,
+ EXT4_SB(sb)->s_mb_prefetch, &prefetch_ios);
+ if (prefetch_ios)
+ ext4_mb_prefetch_fini(sb, elr->lr_next_group,
+ prefetch_ios);
+ trace_ext4_prefetch_bitmaps(sb, group, elr->lr_next_group,
+ prefetch_ios);
+ if (group >= elr->lr_next_group) {
+ ret = 1;
+ if (elr->lr_first_not_zeroed != ngroups &&
+ !sb_rdonly(sb) && test_opt(sb, INIT_INODE_TABLE)) {
+ elr->lr_next_group = elr->lr_first_not_zeroed;
+ elr->lr_mode = EXT4_LI_MODE_ITABLE;
+ ret = 0;
+ }
+ }
+ return ret;
+ }
- for (group = elr->lr_next_group; group < ngroups; group++) {
+ for (; group < ngroups; group++) {
gdp = ext4_get_group_desc(sb, group, NULL);
if (!gdp) {
ret = 1;
@@ -3076,9 +3099,10 @@
timeout = jiffies;
ret = ext4_init_inode_table(sb, group,
elr->lr_timeout ? 0 : 1);
+ trace_ext4_lazy_itable_init(sb, group);
if (elr->lr_timeout == 0) {
timeout = (jiffies - timeout) *
- elr->lr_sbi->s_li_wait_mult;
+ EXT4_SB(elr->lr_super)->s_li_wait_mult;
elr->lr_timeout = timeout;
}
elr->lr_next_sched = jiffies + elr->lr_timeout;
@@ -3093,15 +3117,11 @@
*/
static void ext4_remove_li_request(struct ext4_li_request *elr)
{
- struct ext4_sb_info *sbi;
-
if (!elr)
return;
- sbi = elr->lr_sbi;
-
list_del(&elr->lr_request);
- sbi->s_li_request = NULL;
+ EXT4_SB(elr->lr_super)->s_li_request = NULL;
kfree(elr);
}
@@ -3310,7 +3330,6 @@
static struct ext4_li_request *ext4_li_request_new(struct super_block *sb,
ext4_group_t start)
{
- struct ext4_sb_info *sbi = EXT4_SB(sb);
struct ext4_li_request *elr;
elr = kzalloc(sizeof(*elr), GFP_KERNEL);
@@ -3318,8 +3337,13 @@
return NULL;
elr->lr_super = sb;
- elr->lr_sbi = sbi;
- elr->lr_next_group = start;
+ elr->lr_first_not_zeroed = start;
+ if (test_opt(sb, PREFETCH_BLOCK_BITMAPS))
+ elr->lr_mode = EXT4_LI_MODE_PREFETCH_BBITMAP;
+ else {
+ elr->lr_mode = EXT4_LI_MODE_ITABLE;
+ elr->lr_next_group = start;
+ }
/*
* Randomize first schedule time of the request to
@@ -3337,6 +3361,7 @@
struct ext4_sb_info *sbi = EXT4_SB(sb);
struct ext4_li_request *elr = NULL;
ext4_group_t ngroups = sbi->s_groups_count;
+ enum ext4_li_mode lr_mode = EXT4_LI_MODE_ITABLE;
int ret = 0;
mutex_lock(&ext4_li_mtx);
@@ -3349,8 +3374,10 @@
goto out;
}
- if (first_not_zeroed == ngroups || sb_rdonly(sb) ||
- !test_opt(sb, INIT_INODE_TABLE))
+ if (test_opt(sb, PREFETCH_BLOCK_BITMAPS)) {
+ lr_mode = EXT4_LI_MODE_PREFETCH_BBITMAP;
+ } else if (first_not_zeroed == ngroups || sb_rdonly(sb) ||
+ !test_opt(sb, INIT_INODE_TABLE))
goto out;
elr = ext4_li_request_new(sb, first_not_zeroed);
diff --git a/include/trace/events/ext4.h b/include/trace/events/ext4.h
index a2dd7b0..038f163 100644
--- a/include/trace/events/ext4.h
+++ b/include/trace/events/ext4.h
@@ -2719,6 +2719,50 @@
__entry->function, __entry->line)
);
+TRACE_EVENT(ext4_prefetch_bitmaps,
+ TP_PROTO(struct super_block *sb, ext4_group_t group,
+ ext4_group_t next, unsigned int prefetch_ios),
+
+ TP_ARGS(sb, group, next, prefetch_ios),
+
+ TP_STRUCT__entry(
+ __field( dev_t, dev )
+ __field( __u32, group )
+ __field( __u32, next )
+ __field( __u32, ios )
+ ),
+
+ TP_fast_assign(
+ __entry->dev = sb->s_dev;
+ __entry->group = group;
+ __entry->next = next;
+ __entry->ios = prefetch_ios;
+ ),
+
+ TP_printk("dev %d,%d group %u next %u ios %u",
+ MAJOR(__entry->dev), MINOR(__entry->dev),
+ __entry->group, __entry->next, __entry->ios)
+);
+
+TRACE_EVENT(ext4_lazy_itable_init,
+ TP_PROTO(struct super_block *sb, ext4_group_t group),
+
+ TP_ARGS(sb, group),
+
+ TP_STRUCT__entry(
+ __field( dev_t, dev )
+ __field( __u32, group )
+ ),
+
+ TP_fast_assign(
+ __entry->dev = sb->s_dev;
+ __entry->group = group;
+ ),
+
+ TP_printk("dev %d,%d group %u",
+ MAJOR(__entry->dev), MINOR(__entry->dev), __entry->group)
+);
+
#endif /* _TRACE_EXT4_H */
/* This part must be outside protection */
