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c8b978188c
linux/fs/btrfs/print-tree.c
Chris Mason c8b978188c Btrfs: Add zlib compression support 
This is a large change for adding compression on reading and writing,
both for inline and regular extents.  It does some fairly large
surgery to the writeback paths.

Compression is off by default and enabled by mount -o compress.  Even
when the -o compress mount option is not used, it is possible to read
compressed extents off the disk.

If compression for a given set of pages fails to make them smaller, the
file is flagged to avoid future compression attempts later.

* While finding delalloc extents, the pages are locked before being sent down
to the delalloc handler.  This allows the delalloc handler to do complex things
such as cleaning the pages, marking them writeback and starting IO on their
behalf.

* Inline extents are inserted at delalloc time now.  This allows us to compress
the data before inserting the inline extent, and it allows us to insert
an inline extent that spans multiple pages.

* All of the in-memory extent representations (extent_map.c, ordered-data.c etc)
are changed to record both an in-memory size and an on disk size, as well
as a flag for compression.

From a disk format point of view, the extent pointers in the file are changed
to record the on disk size of a given extent and some encoding flags.
Space in the disk format is allocated for compression encoding, as well
as encryption and a generic 'other' field.  Neither the encryption or the
'other' field are currently used.

In order to limit the amount of data read for a single random read in the
file, the size of a compressed extent is limited to 128k.  This is a
software only limit, the disk format supports u64 sized compressed extents.

In order to limit the ram consumed while processing extents, the uncompressed
size of a compressed extent is limited to 256k.  This is a software only limit
and will be subject to tuning later.

Checksumming is still done on compressed extents, and it is done on the
uncompressed version of the data.  This way additional encodings can be
layered on without having to figure out which encoding to checksum.

Compression happens at delalloc time, which is basically singled threaded because
it is usually done by a single pdflush thread.  This makes it tricky to
spread the compression load across all the cpus on the box.  We'll have to
look at parallel pdflush walks of dirty inodes at a later time.

Decompression is hooked into readpages and it does spread across CPUs nicely.

Signed-off-by: Chris Mason <chris.mason@oracle.com>
2008-10-29 14:49:59 -04:00

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/*
* Copyright (C) 2007 Oracle. All rights reserved.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public
* License v2 as published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* You should have received a copy of the GNU General Public
* License along with this program; if not, write to the
* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
* Boston, MA 021110-1307, USA.
*/
#include "ctree.h"
#include "disk-io.h"
#include "print-tree.h"
static void print_chunk(struct extent_buffer *eb, struct btrfs_chunk *chunk)
{
int num_stripes = btrfs_chunk_num_stripes(eb, chunk);
int i;
printk("\t\tchunk length %llu owner %llu type %llu num_stripes %d\n",
(unsigned long long)btrfs_chunk_length(eb, chunk),
(unsigned long long)btrfs_chunk_owner(eb, chunk),
(unsigned long long)btrfs_chunk_type(eb, chunk),
num_stripes);
for (i = 0 ; i < num_stripes ; i++) {
printk("\t\t\tstripe %d devid %llu offset %llu\n", i,
(unsigned long long)btrfs_stripe_devid_nr(eb, chunk, i),
(unsigned long long)btrfs_stripe_offset_nr(eb, chunk, i));
}
}
static void print_dev_item(struct extent_buffer *eb,
struct btrfs_dev_item *dev_item)
{
printk("\t\tdev item devid %llu "
"total_bytes %llu bytes used %Lu\n",
(unsigned long long)btrfs_device_id(eb, dev_item),
(unsigned long long)btrfs_device_total_bytes(eb, dev_item),
(unsigned long long)btrfs_device_bytes_used(eb, dev_item));
}
void btrfs_print_leaf(struct btrfs_root *root, struct extent_buffer *l)
{
int i;
u32 nr = btrfs_header_nritems(l);
struct btrfs_item *item;
struct btrfs_extent_item *ei;
struct btrfs_root_item *ri;
struct btrfs_dir_item *di;
struct btrfs_inode_item *ii;
struct btrfs_block_group_item *bi;
struct btrfs_file_extent_item *fi;
struct btrfs_key key;
struct btrfs_key found_key;
struct btrfs_extent_ref *ref;
struct btrfs_dev_extent *dev_extent;
u32 type;
printk("leaf %llu total ptrs %d free space %d\n",
(unsigned long long)btrfs_header_bytenr(l), nr,
btrfs_leaf_free_space(root, l));
for (i = 0 ; i < nr ; i++) {
item = btrfs_item_nr(l, i);
btrfs_item_key_to_cpu(l, &key, i);
type = btrfs_key_type(&key);
printk("\titem %d key (%llu %x %llu) itemoff %d itemsize %d\n",
i,
(unsigned long long)key.objectid, type,
(unsigned long long)key.offset,
btrfs_item_offset(l, item), btrfs_item_size(l, item));
switch (type) {
case BTRFS_INODE_ITEM_KEY:
ii = btrfs_item_ptr(l, i, struct btrfs_inode_item);
printk("\t\tinode generation %llu size %llu mode %o\n",
(unsigned long long)btrfs_inode_generation(l, ii),
(unsigned long long)btrfs_inode_size(l, ii),
btrfs_inode_mode(l, ii));
break;
case BTRFS_DIR_ITEM_KEY:
di = btrfs_item_ptr(l, i, struct btrfs_dir_item);
btrfs_dir_item_key_to_cpu(l, di, &found_key);
printk("\t\tdir oid %llu type %u\n",
(unsigned long long)found_key.objectid,
btrfs_dir_type(l, di));
break;
case BTRFS_ROOT_ITEM_KEY:
ri = btrfs_item_ptr(l, i, struct btrfs_root_item);
printk("\t\troot data bytenr %llu refs %u\n",
(unsigned long long)btrfs_disk_root_bytenr(l, ri),
btrfs_disk_root_refs(l, ri));
break;
case BTRFS_EXTENT_ITEM_KEY:
ei = btrfs_item_ptr(l, i, struct btrfs_extent_item);
printk("\t\textent data refs %u\n",
btrfs_extent_refs(l, ei));
break;
case BTRFS_EXTENT_REF_KEY:
ref = btrfs_item_ptr(l, i, struct btrfs_extent_ref);
printk("\t\textent back ref root %llu gen %llu "
"owner %llu num_refs %lu\n",
(unsigned long long)btrfs_ref_root(l, ref),
(unsigned long long)btrfs_ref_generation(l, ref),
(unsigned long long)btrfs_ref_objectid(l, ref),
(unsigned long)btrfs_ref_num_refs(l, ref));
break;
case BTRFS_EXTENT_DATA_KEY:
fi = btrfs_item_ptr(l, i,
struct btrfs_file_extent_item);
if (btrfs_file_extent_type(l, fi) ==
BTRFS_FILE_EXTENT_INLINE) {
printk("\t\tinline extent data size %u\n",
btrfs_file_extent_inline_len(l, fi));
break;
}
printk("\t\textent data disk bytenr %llu nr %llu\n",
(unsigned long long)btrfs_file_extent_disk_bytenr(l, fi),
(unsigned long long)btrfs_file_extent_disk_num_bytes(l, fi));
printk("\t\textent data offset %llu nr %llu ram %llu\n",
(unsigned long long)btrfs_file_extent_offset(l, fi),
(unsigned long long)btrfs_file_extent_num_bytes(l, fi),
(unsigned long long)btrfs_file_extent_ram_bytes(l, fi));
break;
case BTRFS_BLOCK_GROUP_ITEM_KEY:
bi = btrfs_item_ptr(l, i,
struct btrfs_block_group_item);
printk("\t\tblock group used %llu\n",
(unsigned long long)btrfs_disk_block_group_used(l, bi));
break;
case BTRFS_CHUNK_ITEM_KEY:
print_chunk(l, btrfs_item_ptr(l, i, struct btrfs_chunk));
break;
case BTRFS_DEV_ITEM_KEY:
print_dev_item(l, btrfs_item_ptr(l, i,
struct btrfs_dev_item));
break;
case BTRFS_DEV_EXTENT_KEY:
dev_extent = btrfs_item_ptr(l, i,
struct btrfs_dev_extent);
printk("\t\tdev extent chunk_tree %llu\n"
"\t\tchunk objectid %llu chunk offset %llu "
"length %llu\n",
(unsigned long long)
btrfs_dev_extent_chunk_tree(l, dev_extent),
(unsigned long long)
btrfs_dev_extent_chunk_objectid(l, dev_extent),
(unsigned long long)
btrfs_dev_extent_chunk_offset(l, dev_extent),
(unsigned long long)
btrfs_dev_extent_length(l, dev_extent));
};
}
}
void btrfs_print_tree(struct btrfs_root *root, struct extent_buffer *c)
{
int i; u32 nr;
struct btrfs_key key;
int level;
if (!c)
return;
nr = btrfs_header_nritems(c);
level = btrfs_header_level(c);
if (level == 0) {
btrfs_print_leaf(root, c);
return;
}
printk("node %llu level %d total ptrs %d free spc %u\n",
(unsigned long long)btrfs_header_bytenr(c),
btrfs_header_level(c), nr,
(u32)BTRFS_NODEPTRS_PER_BLOCK(root) - nr);
for (i = 0; i < nr; i++) {
btrfs_node_key_to_cpu(c, &key, i);
printk("\tkey %d (%llu %u %llu) block %llu\n",
i,
(unsigned long long)key.objectid,
key.type,
(unsigned long long)key.offset,
(unsigned long long)btrfs_node_blockptr(c, i));
}
for (i = 0; i < nr; i++) {
struct extent_buffer *next = read_tree_block(root,
btrfs_node_blockptr(c, i),
btrfs_level_size(root, level - 1),
btrfs_node_ptr_generation(c, i));
if (btrfs_is_leaf(next) &&
btrfs_header_level(c) != 1)
BUG();
if (btrfs_header_level(next) !=
btrfs_header_level(c) - 1)
BUG();
btrfs_print_tree(root, next);
free_extent_buffer(next);
}
}
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