ext4: make prefetch_block_bitmaps default

Block bitmap prefetching is needed for these allocator optimization
data structures to get populated and provide better group scanning
order. So, turn it on bu default. prefetch_block_bitmaps mount option
is now marked as removed and a new option no_prefetch_block_bitmaps is
added to disable block bitmap prefetching.

Signed-off-by: Harshad Shirwadkar <harshadshirwadkar@gmail.com>
Link: https://lore.kernel.org/r/20210401172129.189766-8-harshadshirwadkar@gmail.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index 369b2d2c8850e8ba1e97341e7fd328075b96c726..a29660db86ac442fca6588583ac4aeea4e22b3dd 100644 (file)
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -1227,7 +1227,7 @@ struct ext4_inode_info {
 #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_NO_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 */

diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 3b12deb93a6b5336187b6a139ab0a74b61e8669c..0f9af7ba921013cbc80c038ddf1479155f76168f 100644 (file)
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -1688,7 +1688,7 @@ enum {
        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, Opt_mb_optimize_scan,
+       Opt_no_prefetch_block_bitmaps, Opt_mb_optimize_scan,
 #ifdef CONFIG_EXT4_DEBUG
        Opt_fc_debug_max_replay, Opt_fc_debug_force
 #endif
@@ -1788,7 +1788,8 @@ static const match_table_t tokens = {
        {Opt_inlinecrypt, "inlinecrypt"},
        {Opt_nombcache, "nombcache"},
        {Opt_nombcache, "no_mbcache"},  /* for backward compatibility */
-       {Opt_prefetch_block_bitmaps, "prefetch_block_bitmaps"},
+       {Opt_removed, "prefetch_block_bitmaps"},
+       {Opt_no_prefetch_block_bitmaps, "no_prefetch_block_bitmaps"},
        {Opt_mb_optimize_scan, "mb_optimize_scan=%d"},
        {Opt_removed, "check=none"},    /* mount option from ext2/3 */
        {Opt_removed, "nocheck"},       /* mount option from ext2/3 */
@@ -2010,7 +2011,7 @@ static const struct mount_opts {
        {Opt_max_dir_size_kb, 0, MOPT_GTE0},
        {Opt_test_dummy_encryption, 0, MOPT_STRING},
        {Opt_nombcache, EXT4_MOUNT_NO_MBCACHE, MOPT_SET},
-       {Opt_prefetch_block_bitmaps, EXT4_MOUNT_PREFETCH_BLOCK_BITMAPS,
+       {Opt_no_prefetch_block_bitmaps, EXT4_MOUNT_NO_PREFETCH_BLOCK_BITMAPS,
         MOPT_SET},
        {Opt_mb_optimize_scan, EXT4_MOUNT2_MB_OPTIMIZE_SCAN, MOPT_GTE0},
 #ifdef CONFIG_EXT4_DEBUG
@@ -3707,11 +3708,11 @@ static struct ext4_li_request *ext4_li_request_new(struct super_block *sb,
 
        elr->lr_super = sb;
        elr->lr_first_not_zeroed = start;
-       if (test_opt(sb, PREFETCH_BLOCK_BITMAPS))
-               elr->lr_mode = EXT4_LI_MODE_PREFETCH_BBITMAP;
-       else {
+       if (test_opt(sb, NO_PREFETCH_BLOCK_BITMAPS)) {
                elr->lr_mode = EXT4_LI_MODE_ITABLE;
                elr->lr_next_group = start;
+       } else {
+               elr->lr_mode = EXT4_LI_MODE_PREFETCH_BBITMAP;
        }
 
        /*
@@ -3742,7 +3743,7 @@ int ext4_register_li_request(struct super_block *sb,
                goto out;
        }
 
-       if (!test_opt(sb, PREFETCH_BLOCK_BITMAPS) &&
+       if (test_opt(sb, NO_PREFETCH_BLOCK_BITMAPS) &&
            (first_not_zeroed == ngroups || sb_rdonly(sb) ||
             !test_opt(sb, INIT_INODE_TABLE)))
                goto out;