linux/fs/btrfs/ordered-data.h
Filipe Manana b659ef0277 Btrfs: avoid syncing log in the fast fsync path when not necessary
Commit 3a8b36f378 ("Btrfs: fix data loss in the fast fsync path") added
a performance regression for that causes an unnecessary sync of the log
trees (fs/subvol and root log trees) when 2 consecutive fsyncs are done
against a file, without no writes or any metadata updates to the inode in
between them and if a transaction is committed before the second fsync is
called.

Huang Ying reported this to lkml (https://lkml.org/lkml/2015/3/18/99)
after a test sysbench test that measured a -62% decrease of file io
requests per second for that tests' workload.

The test is:

  echo performance > /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor
  echo performance > /sys/devices/system/cpu/cpu1/cpufreq/scaling_governor
  echo performance > /sys/devices/system/cpu/cpu2/cpufreq/scaling_governor
  echo performance > /sys/devices/system/cpu/cpu3/cpufreq/scaling_governor
  mkfs -t btrfs /dev/sda2
  mount -t btrfs /dev/sda2 /fs/sda2
  cd /fs/sda2
  for ((i = 0; i < 1024; i++)); do fallocate -l 67108864 testfile.$i; done
  sysbench --test=fileio --max-requests=0 --num-threads=4 --max-time=600 \
    --file-test-mode=rndwr --file-total-size=68719476736 --file-io-mode=sync \
    --file-num=1024 run

A test on kvm guest, running a debug kernel gave me the following results:

Without 3a8b36f378:             16.01 reqs/sec
With 3a8b36f378:                 3.39 reqs/sec
With 3a8b36f378 and this patch: 16.04 reqs/sec

Reported-by: Huang Ying <ying.huang@intel.com>
Tested-by: Huang, Ying <ying.huang@intel.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Chris Mason <clm@fb.com>
2015-06-10 07:02:43 -07:00

213 lines
6.8 KiB
C

/*
* 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 {
/* 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 */
#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 */
#define BTRFS_ORDERED_LOGGED 10 /* Set when we've waited on this ordered extent
* in the logging code. */
struct btrfs_ordered_extent {
/* logical offset in the file */
u64 file_offset;
/* disk byte number */
u64 start;
/* ram length of the extent in bytes */
u64 len;
/* extent length on disk */
u64 disk_len;
/* number of bytes that still need writing */
u64 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;
/* If the transaction needs to wait on this ordered extent */
struct list_head trans_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);
bool btrfs_have_ordered_extents_in_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,
const loff_t start,
const loff_t end);
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_trans_handle *trans,
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