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fs: ext4: cache extent data
When a file contains extents, U-Boot currently reads extent-related data
for each block in the file, even if that data is located in the same
block each time. This significantly slows down loading of files that use
extents. Implement a very dumb cache to prevent repeatedly reading the
same block. Files with extents now load as fast as files without.

Note: There are many cases where read_allocated_block() is called. This
patch only addresses one of those places; all others still read redundant
data in any case they did before. This is a minimal patch to fix the
load command; other cases aren't fixed.

Signed-off-by: Stephen Warren <swarren@nvidia.com>
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nvswarren authored and trini committed Apr 9, 2019
1 parent 4c24dab commit d5aee65
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Showing 5 changed files with 99 additions and 37 deletions.
45 changes: 27 additions & 18 deletions fs/ext4/ext4_common.c
Expand Up @@ -510,7 +510,8 @@ int ext4fs_update_parent_dentry(char *filename, int file_type)

restart_read:
/* read the block no allocated to a file */
first_block_no_of_root = read_allocated_block(g_parent_inode, blk_idx);
first_block_no_of_root = read_allocated_block(g_parent_inode, blk_idx,
NULL);
if (first_block_no_of_root <= 0)
goto fail;

Expand Down Expand Up @@ -646,7 +647,7 @@ static int search_dir(struct ext2_inode *parent_inode, char *dirname)

/* get the block no allocated to a file */
for (blk_idx = 0; blk_idx < directory_blocks; blk_idx++) {
blknr = read_allocated_block(parent_inode, blk_idx);
blknr = read_allocated_block(parent_inode, blk_idx, NULL);
if (blknr <= 0)
goto fail;

Expand Down Expand Up @@ -943,7 +944,7 @@ int ext4fs_filename_unlink(char *filename)

/* read the block no allocated to a file */
for (blk_idx = 0; blk_idx < directory_blocks; blk_idx++) {
blknr = read_allocated_block(g_parent_inode, blk_idx);
blknr = read_allocated_block(g_parent_inode, blk_idx, NULL);
if (blknr <= 0)
break;
inodeno = unlink_filename(filename, blknr);
Expand Down Expand Up @@ -1522,7 +1523,7 @@ void ext4fs_allocate_blocks(struct ext2_inode *file_inode,
#endif

static struct ext4_extent_header *ext4fs_get_extent_block
(struct ext2_data *data, char *buf,
(struct ext2_data *data, struct ext_block_cache *cache,
struct ext4_extent_header *ext_block,
uint32_t fileblock, int log2_blksz)
{
Expand Down Expand Up @@ -1551,12 +1552,10 @@ static struct ext4_extent_header *ext4fs_get_extent_block

block = le16_to_cpu(index[i].ei_leaf_hi);
block = (block << 32) + le32_to_cpu(index[i].ei_leaf_lo);

if (ext4fs_devread((lbaint_t)block << log2_blksz, 0, blksz,
buf))
ext_block = (struct ext4_extent_header *)buf;
else
block <<= log2_blksz;
if (!ext_cache_read(cache, (lbaint_t)block, blksz))
return NULL;
ext_block = (struct ext4_extent_header *)cache->buf;
}
}

Expand Down Expand Up @@ -1613,7 +1612,8 @@ int ext4fs_read_inode(struct ext2_data *data, int ino, struct ext2_inode *inode)
return 1;
}

long int read_allocated_block(struct ext2_inode *inode, int fileblock)
long int read_allocated_block(struct ext2_inode *inode, int fileblock,
struct ext_block_cache *cache)
{
long int blknr;
int blksz;
Expand All @@ -1630,20 +1630,26 @@ long int read_allocated_block(struct ext2_inode *inode, int fileblock)

if (le32_to_cpu(inode->flags) & EXT4_EXTENTS_FL) {
long int startblock, endblock;
char *buf = zalloc(blksz);
if (!buf)
return -ENOMEM;
struct ext_block_cache *c, cd;
struct ext4_extent_header *ext_block;
struct ext4_extent *extent;
int i;

if (cache) {
c = cache;
} else {
c = &cd;
ext_cache_init(c);
}
ext_block =
ext4fs_get_extent_block(ext4fs_root, buf,
ext4fs_get_extent_block(ext4fs_root, c,
(struct ext4_extent_header *)
inode->b.blocks.dir_blocks,
fileblock, log2_blksz);
if (!ext_block) {
printf("invalid extent block\n");
free(buf);
if (!cache)
ext_cache_fini(c);
return -EINVAL;
}

Expand All @@ -1655,19 +1661,22 @@ long int read_allocated_block(struct ext2_inode *inode, int fileblock)

if (startblock > fileblock) {
/* Sparse file */
free(buf);
if (!cache)
ext_cache_fini(c);
return 0;

} else if (fileblock < endblock) {
start = le16_to_cpu(extent[i].ee_start_hi);
start = (start << 32) +
le32_to_cpu(extent[i].ee_start_lo);
free(buf);
if (!cache)
ext_cache_fini(c);
return (fileblock - startblock) + start;
}
}

free(buf);
if (!cache)
ext_cache_fini(c);
return 0;
}

Expand Down
22 changes: 12 additions & 10 deletions fs/ext4/ext4_journal.c
Expand Up @@ -347,7 +347,7 @@ void recover_transaction(int prev_desc_logical_no)
ext4fs_read_inode(ext4fs_root, EXT2_JOURNAL_INO,
(struct ext2_inode *)&inode_journal);
blknr = read_allocated_block((struct ext2_inode *)
&inode_journal, i);
&inode_journal, i, NULL);
ext4fs_devread((lbaint_t)blknr * fs->sect_perblk, 0, fs->blksz,
temp_buff);
p_jdb = (char *)temp_buff;
Expand All @@ -372,7 +372,7 @@ void recover_transaction(int prev_desc_logical_no)
be32_to_cpu(jdb->h_sequence)) == 0)
continue;
}
blknr = read_allocated_block(&inode_journal, i);
blknr = read_allocated_block(&inode_journal, i, NULL);
ext4fs_devread((lbaint_t)blknr * fs->sect_perblk, 0,
fs->blksz, metadata_buff);
put_ext4((uint64_t)((uint64_t)be32_to_cpu(tag->block) * (uint64_t)fs->blksz),
Expand Down Expand Up @@ -419,7 +419,8 @@ int ext4fs_check_journal_state(int recovery_flag)
}

ext4fs_read_inode(ext4fs_root, EXT2_JOURNAL_INO, &inode_journal);
blknr = read_allocated_block(&inode_journal, EXT2_JOURNAL_SUPERBLOCK);
blknr = read_allocated_block(&inode_journal, EXT2_JOURNAL_SUPERBLOCK,
NULL);
ext4fs_devread((lbaint_t)blknr * fs->sect_perblk, 0, fs->blksz,
temp_buff);
jsb = (struct journal_superblock_t *) temp_buff;
Expand All @@ -443,7 +444,7 @@ int ext4fs_check_journal_state(int recovery_flag)

i = be32_to_cpu(jsb->s_first);
while (1) {
blknr = read_allocated_block(&inode_journal, i);
blknr = read_allocated_block(&inode_journal, i, NULL);
memset(temp_buff1, '\0', fs->blksz);
ext4fs_devread((lbaint_t)blknr * fs->sect_perblk,
0, fs->blksz, temp_buff1);
Expand Down Expand Up @@ -537,7 +538,7 @@ int ext4fs_check_journal_state(int recovery_flag)
ext4_read_superblock((char *)fs->sb);

blknr = read_allocated_block(&inode_journal,
EXT2_JOURNAL_SUPERBLOCK);
EXT2_JOURNAL_SUPERBLOCK, NULL);
put_ext4((uint64_t) ((uint64_t)blknr * (uint64_t)fs->blksz),
(struct journal_superblock_t *)temp_buff,
(uint32_t) fs->blksz);
Expand Down Expand Up @@ -566,7 +567,7 @@ static void update_descriptor_block(long int blknr)

ext4fs_read_inode(ext4fs_root, EXT2_JOURNAL_INO, &inode_journal);
jsb_blknr = read_allocated_block(&inode_journal,
EXT2_JOURNAL_SUPERBLOCK);
EXT2_JOURNAL_SUPERBLOCK, NULL);
ext4fs_devread((lbaint_t)jsb_blknr * fs->sect_perblk, 0, fs->blksz,
temp_buff);
jsb = (struct journal_superblock_t *) temp_buff;
Expand Down Expand Up @@ -618,7 +619,7 @@ static void update_commit_block(long int blknr)
ext4fs_read_inode(ext4fs_root, EXT2_JOURNAL_INO,
&inode_journal);
jsb_blknr = read_allocated_block(&inode_journal,
EXT2_JOURNAL_SUPERBLOCK);
EXT2_JOURNAL_SUPERBLOCK, NULL);
ext4fs_devread((lbaint_t)jsb_blknr * fs->sect_perblk, 0, fs->blksz,
temp_buff);
jsb = (struct journal_superblock_t *) temp_buff;
Expand All @@ -645,16 +646,17 @@ void ext4fs_update_journal(void)
long int blknr;
int i;
ext4fs_read_inode(ext4fs_root, EXT2_JOURNAL_INO, &inode_journal);
blknr = read_allocated_block(&inode_journal, jrnl_blk_idx++);
blknr = read_allocated_block(&inode_journal, jrnl_blk_idx++, NULL);
update_descriptor_block(blknr);
for (i = 0; i < MAX_JOURNAL_ENTRIES; i++) {
if (journal_ptr[i]->blknr == -1)
break;
blknr = read_allocated_block(&inode_journal, jrnl_blk_idx++);
blknr = read_allocated_block(&inode_journal, jrnl_blk_idx++,
NULL);
put_ext4((uint64_t) ((uint64_t)blknr * (uint64_t)fs->blksz),
journal_ptr[i]->buf, fs->blksz);
}
blknr = read_allocated_block(&inode_journal, jrnl_blk_idx++);
blknr = read_allocated_block(&inode_journal, jrnl_blk_idx++, NULL);
update_commit_block(blknr);
printf("update journal finished\n");
}
6 changes: 3 additions & 3 deletions fs/ext4/ext4_write.c
Expand Up @@ -479,7 +479,7 @@ static int ext4fs_delete_file(int inodeno)

/* release data blocks */
for (i = 0; i < no_blocks; i++) {
blknr = read_allocated_block(&inode, i);
blknr = read_allocated_block(&inode, i, NULL);
if (blknr == 0)
continue;
if (blknr < 0)
Expand Down Expand Up @@ -695,7 +695,7 @@ void ext4fs_deinit(void)
ext4fs_read_inode(ext4fs_root, EXT2_JOURNAL_INO,
&inode_journal);
blknr = read_allocated_block(&inode_journal,
EXT2_JOURNAL_SUPERBLOCK);
EXT2_JOURNAL_SUPERBLOCK, NULL);
ext4fs_devread((lbaint_t)blknr * fs->sect_perblk, 0, fs->blksz,
temp_buff);
jsb = (struct journal_superblock_t *)temp_buff;
Expand Down Expand Up @@ -776,7 +776,7 @@ static int ext4fs_write_file(struct ext2_inode *file_inode,
long int blknr;
int blockend = fs->blksz;
int skipfirst = 0;
blknr = read_allocated_block(file_inode, i);
blknr = read_allocated_block(file_inode, i, NULL);
if (blknr <= 0)
return -1;

Expand Down
51 changes: 46 additions & 5 deletions fs/ext4/ext4fs.c
Expand Up @@ -62,6 +62,9 @@ int ext4fs_read_file(struct ext2fs_node *node, loff_t pos,
lbaint_t delayed_next = 0;
char *delayed_buf = NULL;
short status;
struct ext_block_cache cache;

ext_cache_init(&cache);

if (blocksize <= 0)
return -1;
Expand All @@ -77,9 +80,11 @@ int ext4fs_read_file(struct ext2fs_node *node, loff_t pos,
int blockoff = pos - (blocksize * i);
int blockend = blocksize;
int skipfirst = 0;
blknr = read_allocated_block(&(node->inode), i);
if (blknr < 0)
blknr = read_allocated_block(&node->inode, i, &cache);
if (blknr < 0) {
ext_cache_fini(&cache);
return -1;
}

blknr = blknr << log2_fs_blocksize;

Expand Down Expand Up @@ -109,8 +114,10 @@ int ext4fs_read_file(struct ext2fs_node *node, loff_t pos,
delayed_skipfirst,
delayed_extent,
delayed_buf);
if (status == 0)
if (status == 0) {
ext_cache_fini(&cache);
return -1;
}
previous_block_number = blknr;
delayed_start = blknr;
delayed_extent = blockend;
Expand All @@ -136,8 +143,10 @@ int ext4fs_read_file(struct ext2fs_node *node, loff_t pos,
delayed_skipfirst,
delayed_extent,
delayed_buf);
if (status == 0)
if (status == 0) {
ext_cache_fini(&cache);
return -1;
}
previous_block_number = -1;
}
/* Zero no more than `len' bytes. */
Expand All @@ -153,12 +162,15 @@ int ext4fs_read_file(struct ext2fs_node *node, loff_t pos,
status = ext4fs_devread(delayed_start,
delayed_skipfirst, delayed_extent,
delayed_buf);
if (status == 0)
if (status == 0) {
ext_cache_fini(&cache);
return -1;
}
previous_block_number = -1;
}

*actread = len;
ext_cache_fini(&cache);
return 0;
}

Expand Down Expand Up @@ -252,3 +264,32 @@ int ext4fs_uuid(char *uuid_str)
return -ENOSYS;
#endif
}

void ext_cache_init(struct ext_block_cache *cache)
{
memset(cache, 0, sizeof(*cache));
}

void ext_cache_fini(struct ext_block_cache *cache)
{
free(cache->buf);
ext_cache_init(cache);
}

int ext_cache_read(struct ext_block_cache *cache, lbaint_t block, int size)
{
/* This could be more lenient, but this is simple and enough for now */
if (cache->buf && cache->block == block && cache->size == size)
return 1;
ext_cache_fini(cache);
cache->buf = malloc(size);
if (!cache->buf)
return 0;
if (!ext4fs_devread(block, 0, size, cache->buf)) {
free(cache->buf);
return 0;
}
cache->block = block;
cache->size = size;
return 1;
}
12 changes: 11 additions & 1 deletion include/ext4fs.h
Expand Up @@ -117,6 +117,12 @@ struct ext_filesystem {
struct blk_desc *dev_desc;
};

struct ext_block_cache {
char *buf;
lbaint_t block;
int size;
};

extern struct ext2_data *ext4fs_root;
extern struct ext2fs_node *ext4fs_file;

Expand Down Expand Up @@ -146,11 +152,15 @@ int ext4fs_size(const char *filename, loff_t *size);
void ext4fs_free_node(struct ext2fs_node *node, struct ext2fs_node *currroot);
int ext4fs_devread(lbaint_t sector, int byte_offset, int byte_len, char *buf);
void ext4fs_set_blk_dev(struct blk_desc *rbdd, disk_partition_t *info);
long int read_allocated_block(struct ext2_inode *inode, int fileblock);
long int read_allocated_block(struct ext2_inode *inode, int fileblock,
struct ext_block_cache *cache);
int ext4fs_probe(struct blk_desc *fs_dev_desc,
disk_partition_t *fs_partition);
int ext4_read_file(const char *filename, void *buf, loff_t offset, loff_t len,
loff_t *actread);
int ext4_read_superblock(char *buffer);
int ext4fs_uuid(char *uuid_str);
void ext_cache_init(struct ext_block_cache *cache);
void ext_cache_fini(struct ext_block_cache *cache);
int ext_cache_read(struct ext_block_cache *cache, lbaint_t block, int size);
#endif

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