linux_old1/fs/btrfs/ordered-data.h

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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.
*/
#ifndef __BTRFS_ORDERED_DATA__
#define __BTRFS_ORDERED_DATA__
/* one of these per inode */
struct btrfs_ordered_inode_tree {
spinlock_t lock;
struct rb_root tree;
struct rb_node *last;
};
struct btrfs_ordered_sum {
Btrfs: move data checksumming into a dedicated tree Btrfs stores checksums for each data block. Until now, they have been stored in the subvolume trees, indexed by the inode that is referencing the data block. This means that when we read the inode, we've probably read in at least some checksums as well. But, this has a few problems: * The checksums are indexed by logical offset in the file. When compression is on, this means we have to do the expensive checksumming on the uncompressed data. It would be faster if we could checksum the compressed data instead. * If we implement encryption, we'll be checksumming the plain text and storing that on disk. This is significantly less secure. * For either compression or encryption, we have to get the plain text back before we can verify the checksum as correct. This makes the raid layer balancing and extent moving much more expensive. * It makes the front end caching code more complex, as we have touch the subvolume and inodes as we cache extents. * There is potentitally one copy of the checksum in each subvolume referencing an extent. The solution used here is to store the extent checksums in a dedicated tree. This allows us to index the checksums by phyiscal extent start and length. It means: * The checksum is against the data stored on disk, after any compression or encryption is done. * The checksum is stored in a central location, and can be verified without following back references, or reading inodes. This makes compression significantly faster by reducing the amount of data that needs to be checksummed. It will also allow much faster raid management code in general. The checksums are indexed by a key with a fixed objectid (a magic value in ctree.h) and offset set to the starting byte of the extent. This allows us to copy the checksum items into the fsync log tree directly (or any other tree), without having to invent a second format for them. Signed-off-by: Chris Mason <chris.mason@oracle.com>
2008-12-09 05:58:54 +08:00
/* bytenr is the start of this extent on disk */
u64 bytenr;
/*
* this is the length in bytes covered by the sums array below.
*/
int len;
struct list_head list;
/* last field is a variable length array of csums */
u32 sums[];
};
/*
* bits for the flags field:
*
* BTRFS_ORDERED_IO_DONE is set when all of the blocks are written.
* It is used to make sure metadata is inserted into the tree only once
* per extent.
*
* BTRFS_ORDERED_COMPLETE is set when the extent is removed from the
* rbtree, just before waking any waiters. It is used to indicate the
* IO is done and any metadata is inserted into the tree.
*/
#define BTRFS_ORDERED_IO_DONE 0 /* set when all the pages are written */
#define BTRFS_ORDERED_COMPLETE 1 /* set when removed from the tree */
#define BTRFS_ORDERED_NOCOW 2 /* set when we want to write in place */
#define BTRFS_ORDERED_COMPRESSED 3 /* writing a zlib compressed extent */
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>
2008-10-30 02:49:59 +08:00
#define BTRFS_ORDERED_PREALLOC 4 /* set when writing to prealloced extent */
#define BTRFS_ORDERED_DIRECT 5 /* set when we're doing DIO with this extent */
#define BTRFS_ORDERED_IOERR 6 /* We had an io error when writing this out */
#define BTRFS_ORDERED_UPDATED_ISIZE 7 /* indicates whether this ordered extent
* has done its due diligence in updating
* the isize. */
#define BTRFS_ORDERED_LOGGED_CSUM 8 /* We've logged the csums on this ordered
ordered extent */
#define BTRFS_ORDERED_TRUNCATED 9 /* Set when we have to truncate an extent */
struct btrfs_ordered_extent {
/* logical offset in the file */
u64 file_offset;
/* disk byte number */
u64 start;
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>
2008-10-30 02:49:59 +08:00
/* ram length of the extent in bytes */
u64 len;
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>
2008-10-30 02:49:59 +08:00
/* extent length on disk */
u64 disk_len;
/* number of bytes that still need writing */
u64 bytes_left;
/* number of bytes that still need csumming */
u64 csum_bytes_left;
/*
* the end of the ordered extent which is behind it but
* didn't update disk_i_size. Please see the comment of
* btrfs_ordered_update_i_size();
*/
u64 outstanding_isize;
/*
* If we get truncated we need to adjust the file extent we enter for
* this ordered extent so that we do not expose stale data.
*/
u64 truncated_len;
/* flags (described above) */
unsigned long flags;
/* compression algorithm */
int compress_type;
/* reference count */
atomic_t refs;
/* the inode we belong to */
struct inode *inode;
/* list of checksums for insertion when the extent io is done */
struct list_head list;
/* If we need to wait on this to be done */
struct list_head log_list;
/* used to wait for the BTRFS_ORDERED_COMPLETE bit */
wait_queue_head_t wait;
/* our friendly rbtree entry */
struct rb_node rb_node;
/* a per root list of all the pending ordered extents */
struct list_head root_extent_list;
struct btrfs_work work;
struct completion completion;
struct btrfs_work flush_work;
struct list_head work_list;
};
/*
* calculates the total size you need to allocate for an ordered sum
* structure spanning 'bytes' in the file
*/
static inline int btrfs_ordered_sum_size(struct btrfs_root *root,
unsigned long bytes)
{
int num_sectors = (int)DIV_ROUND_UP(bytes, root->sectorsize);
return sizeof(struct btrfs_ordered_sum) + num_sectors * sizeof(u32);
}
static inline void
btrfs_ordered_inode_tree_init(struct btrfs_ordered_inode_tree *t)
{
spin_lock_init(&t->lock);
t->tree = RB_ROOT;
t->last = NULL;
}
void btrfs_put_ordered_extent(struct btrfs_ordered_extent *entry);
void btrfs_remove_ordered_extent(struct inode *inode,
struct btrfs_ordered_extent *entry);
int btrfs_dec_test_ordered_pending(struct inode *inode,
struct btrfs_ordered_extent **cached,
u64 file_offset, u64 io_size, int uptodate);
int btrfs_dec_test_first_ordered_pending(struct inode *inode,
struct btrfs_ordered_extent **cached,
u64 *file_offset, u64 io_size,
int uptodate);
int btrfs_add_ordered_extent(struct inode *inode, u64 file_offset,
u64 start, u64 len, u64 disk_len, int type);
int btrfs_add_ordered_extent_dio(struct inode *inode, u64 file_offset,
u64 start, u64 len, u64 disk_len, int type);
int btrfs_add_ordered_extent_compress(struct inode *inode, u64 file_offset,
u64 start, u64 len, u64 disk_len,
int type, int compress_type);
void btrfs_add_ordered_sum(struct inode *inode,
struct btrfs_ordered_extent *entry,
struct btrfs_ordered_sum *sum);
struct btrfs_ordered_extent *btrfs_lookup_ordered_extent(struct inode *inode,
u64 file_offset);
void btrfs_start_ordered_extent(struct inode *inode,
struct btrfs_ordered_extent *entry, int wait);
int btrfs_wait_ordered_range(struct inode *inode, u64 start, u64 len);
struct btrfs_ordered_extent *
btrfs_lookup_first_ordered_extent(struct inode * inode, u64 file_offset);
struct btrfs_ordered_extent *btrfs_lookup_ordered_range(struct inode *inode,
u64 file_offset,
u64 len);
int btrfs_ordered_update_i_size(struct inode *inode, u64 offset,
struct btrfs_ordered_extent *ordered);
int btrfs_find_ordered_sum(struct inode *inode, u64 offset, u64 disk_bytenr,
u32 *sum, int len);
int btrfs_wait_ordered_extents(struct btrfs_root *root, int nr);
void btrfs_wait_ordered_roots(struct btrfs_fs_info *fs_info, int nr);
void btrfs_get_logged_extents(struct inode *inode,
struct list_head *logged_list);
void btrfs_put_logged_extents(struct list_head *logged_list);
void btrfs_submit_logged_extents(struct list_head *logged_list,
struct btrfs_root *log);
void btrfs_wait_logged_extents(struct btrfs_root *log, u64 transid);
void btrfs_free_logged_extents(struct btrfs_root *log, u64 transid);
int __init ordered_data_init(void);
void ordered_data_exit(void);
#endif