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Date: Fri, 3 Mar 2017 12:15:48 +0300
From: Artem Blagodarenko <artem.blagodarenko@...il.com>
To: linux-ext4@...r.kernel.org
Cc: adilger.kernel@...ger.ca, alexey.lyashkov@...il.com
Subject: [PATCH] libext2fs: preload block group on request
From: Artem Blagodarenko <artem.blagodarenko@...gate.com>
I send this for descussion. Requested by Andreas Dilger and Alexey Lyashkov.
> But again - I may ask an Artem submit a patch to read GD by demand as =
>it ready again, but it don=E2=80=99t like it due a complexity.
>Sure, it would be good to send it to the list, just to see where =
>complexity is and discuss how it might be fixed.
---
lib/ext2fs/blknum.c | 47 +++++++++++++++++++++++++++++++++++++++++++++--
lib/ext2fs/ext2_fs.h | 1 +
lib/ext2fs/ext2fs.h | 1 +
lib/ext2fs/openfs.c | 27 ++++++---------------------
4 files changed, 53 insertions(+), 23 deletions(-)
diff --git a/lib/ext2fs/blknum.c b/lib/ext2fs/blknum.c
index ac80849..b171bac 100644
--- a/lib/ext2fs/blknum.c
+++ b/lib/ext2fs/blknum.c
@@ -186,8 +186,51 @@ struct ext2_group_desc *ext2fs_group_desc(ext2_filsys fs,
dgrp_t group)
{
int desc_size = EXT2_DESC_SIZE(fs->super) & ~7;
-
- return (struct ext2_group_desc *)((char *)gdp + group * desc_size);
+ struct ext2_group_desc *ret_gdp;
+ struct ext2_group_desc *tmp_gdp;
+ char *dest;
+ dgrp_t block;
+ blk64_t blk;
+ int retval;
+ unsigned int i;
+ unsigned int groups_per_block = EXT2_DESC_PER_BLOCK(fs->super);
+
+ ret_gdp = (struct ext2_group_desc *)((char *)gdp + group * desc_size);
+
+ if ((ret_gdp->bg_flags & EXT2_BG_READ) == 0) {
+ block = group / groups_per_block;
+ blk = ext2fs_descriptor_block_loc2(fs, fs->group_block, block);
+ dest = (char *) gdp + fs->blocksize * block;
+ retval = io_channel_read_blk64(fs->io, blk, 1, dest);
+ if (retval)
+ return NULL;
+
+ tmp_gdp = (struct ext2_group_desc *)dest;
+
+ for (i=0; i < groups_per_block; i++) {
+ /*
+ * TDB: If recovery is from backup superblock, Clear
+ * _UNININT flags & reset bg_itable_unused to zero
+ */
+#ifdef WORDS_BIGENDIAN
+ ext2fs_swap_group_desc2(fs, tmp_gdp);
+#endif
+ tmp_gdp->bg_flags |= EXT2_BG_READ;
+
+ if (fs->orig_super == 0 &&
+ EXT2_HAS_RO_COMPAT_FEATURE(fs->super,
+ EXT4_FEATURE_RO_COMPAT_GDT_CSUM)) {
+ ext2fs_bg_flags_clear(fs, block * groups_per_block + i, EXT2_BG_BLOCK_UNINIT);
+ ext2fs_bg_flags_clear(fs, block * groups_per_block + i, EXT2_BG_INODE_UNINIT);
+ ext2fs_bg_itable_unused_set(fs, block * groups_per_block + i, 0);
+ // The checksum will be reset later, but fix it here
+ // anyway to avoid printing a lot of spurious errors.
+ ext2fs_group_desc_csum_set(fs, block * groups_per_block + i);
+ }
+ tmp_gdp = (struct ext2_group_desc *)((char *)tmp_gdp + EXT2_DESC_SIZE(fs->super));
+ }
+ }
+ return ret_gdp;
}
/* Do the same but as an ext4 group desc for internal use here */
diff --git a/lib/ext2fs/ext2_fs.h b/lib/ext2fs/ext2_fs.h
index 27a7d3a..4858684 100644
--- a/lib/ext2fs/ext2_fs.h
+++ b/lib/ext2fs/ext2_fs.h
@@ -202,6 +202,7 @@ struct ext4_group_desc
#define EXT2_BG_INODE_UNINIT 0x0001 /* Inode table/bitmap not initialized */
#define EXT2_BG_BLOCK_UNINIT 0x0002 /* Block bitmap not initialized */
#define EXT2_BG_INODE_ZEROED 0x0004 /* On-disk itable initialized to zero */
+#define EXT2_BG_READ 0x0008 /* Block group was read from disk */
/*
* Data structures used by the directory indexing feature
diff --git a/lib/ext2fs/ext2fs.h b/lib/ext2fs/ext2fs.h
index 8ff49ca..0ae5cbe 100644
--- a/lib/ext2fs/ext2fs.h
+++ b/lib/ext2fs/ext2fs.h
@@ -221,6 +221,7 @@ struct struct_ext2_filsys {
int fragsize;
dgrp_t group_desc_count;
unsigned long desc_blocks;
+ blk64_t group_block;
struct opaque_ext2_group_desc * group_desc;
unsigned int inode_blocks_per_group;
ext2fs_inode_bitmap inode_map;
diff --git a/lib/ext2fs/openfs.c b/lib/ext2fs/openfs.c
index ba39e01..5f6cda5 100644
--- a/lib/ext2fs/openfs.c
+++ b/lib/ext2fs/openfs.c
@@ -121,11 +121,9 @@ errcode_t ext2fs_open2(const char *name, const char *io_options,
blk64_t group_block, blk;
char *dest, *cp;
int group_zero_adjust = 0;
-#ifdef WORDS_BIGENDIAN
unsigned int groups_per_block;
struct ext2_group_desc *gdp;
int j;
-#endif
EXT2_CHECK_MAGIC(manager, EXT2_ET_MAGIC_IO_MANAGER);
@@ -412,40 +410,27 @@ errcode_t ext2fs_open2(const char *name, const char *io_options,
first_meta_bg, dest);
if (retval)
goto cleanup;
-#ifdef WORDS_BIGENDIAN
- gdp = (struct ext2_group_desc *) dest;
for (j=0; j < groups_per_block*first_meta_bg; j++) {
gdp = ext2fs_group_desc(fs, fs->group_desc, j);
- ext2fs_swap_group_desc2(fs, gdp);
- }
-#endif
- dest += fs->blocksize*first_meta_bg;
- }
- for (i=first_meta_bg ; i < fs->desc_blocks; i++) {
- blk = ext2fs_descriptor_block_loc2(fs, group_block, i);
- retval = io_channel_read_blk64(fs->io, blk, 1, dest);
- if (retval)
- goto cleanup;
#ifdef WORDS_BIGENDIAN
- for (j=0; j < groups_per_block; j++) {
- gdp = ext2fs_group_desc(fs, fs->group_desc,
- i * groups_per_block + j);
ext2fs_swap_group_desc2(fs, gdp);
- }
#endif
- dest += fs->blocksize;
+ gdp->bg_flags |= EXT2_BG_READ;
+ }
+ dest += fs->blocksize*first_meta_bg;
}
+ fs->group_block = group_block;
fs->stride = fs->super->s_raid_stride;
/*
* If recovery is from backup superblock, Clear _UNININT flags &
* reset bg_itable_unused to zero
*/
- if (superblock > 1 && ext2fs_has_group_desc_csum(fs)) {
+ if (first_meta_bg && superblock > 1 && ext2fs_has_group_desc_csum(fs)) {
dgrp_t group;
- for (group = 0; group < fs->group_desc_count; group++) {
+ for (group = 0; group < groups_per_block*first_meta_bg; group++) {
ext2fs_bg_flags_clear(fs, group, EXT2_BG_BLOCK_UNINIT);
ext2fs_bg_flags_clear(fs, group, EXT2_BG_INODE_UNINIT);
ext2fs_bg_itable_unused_set(fs, group, 0);
--
1.7.1
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