mirrors/linux-stable
1
0
Fork 0
mirror of https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git synced 2024-10-29 23:53:32 +00:00
Code Issues Releases Wiki Activity
linux-stable/fs/btrfs/free-space-cache.h

127 lines
4.6 KiB
C
Raw Normal View History

Btrfs: rework allocation clustering Because btrfs is copy-on-write, we end up picking new locations for blocks very often. This makes it fairly difficult to maintain perfect read patterns over time, but we can at least do some optimizations for writes. This is done today by remembering the last place we allocated and trying to find a free space hole big enough to hold more than just one allocation. The end result is that we tend to write sequentially to the drive. This happens all the time for metadata and it happens for data when mounted -o ssd. But, the way we record it is fairly racey and it tends to fragment the free space over time because we are trying to allocate fairly large areas at once. This commit gets rid of the races by adding a free space cluster object with dedicated locking to make sure that only one process at a time is out replacing the cluster. The free space fragmentation is somewhat solved by allowing a cluster to be comprised of smaller free space extents. This part definitely adds some CPU time to the cluster allocations, but it allows the allocator to consume the small holes left behind by cow. Signed-off-by: Chris Mason <chris.mason@oracle.com>
2009-04-03 13:47:43 +00:00
/*
* Copyright (C) 2009 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_FREE_SPACE_CACHE
#define __BTRFS_FREE_SPACE_CACHE
Btrfs: use hybrid extents+bitmap rb tree for free space Currently btrfs has a problem where it can use a ridiculous amount of RAM simply tracking free space. As free space gets fragmented, we end up with thousands of entries on an rb-tree per block group, which usually spans 1 gig of area. Since we currently don't ever flush free space cache back to disk this gets to be a bit unweildly on large fs's with lots of fragmentation. This patch solves this problem by using PAGE_SIZE bitmaps for parts of the free space cache. Initially we calculate a threshold of extent entries we can handle, which is however many extent entries we can cram into 16k of ram. The maximum amount of RAM that should ever be used to track 1 gigabyte of diskspace will be 32k of RAM, which scales much better than we did before. Once we pass the extent threshold, we start adding bitmaps and using those instead for tracking the free space. This patch also makes it so that any free space thats less than 4 * sectorsize we go ahead and put into a bitmap. This is nice since we try and allocate out of the front of a block group, so if the front of a block group is heavily fragmented and then has a huge chunk of free space at the end, we go ahead and add the fragmented areas to bitmaps and use a normal extent entry to track the big chunk at the back of the block group. I've also taken the opportunity to revamp how we search for free space. Previously we indexed free space via an offset indexed rb tree and a bytes indexed rb tree. I've dropped the bytes indexed rb tree and use only the offset indexed rb tree. This cuts the number of tree operations we were doing previously down by half, and gives us a little bit of a better allocation pattern since we will always start from a specific offset and search forward from there, instead of searching for the size we need and try and get it as close as possible to the offset we want. I've given this a healthy amount of testing pre-new format stuff, as well as post-new format stuff. I've booted up my fedora box which is installed on btrfs with this patch and ran with it for a few days without issues. I've not seen any performance regressions in any of my tests. Since the last patch Yan Zheng fixed a problem where we could have overlapping entries, so updating their offset inline would cause problems. Thanks, Signed-off-by: Josef Bacik <jbacik@redhat.com> Signed-off-by: Chris Mason <chris.mason@oracle.com>
2009-07-14 01:29:25 +00:00
struct btrfs_free_space {
struct rb_node offset_index;
u64 offset;
u64 bytes;
unsigned long *bitmap;
struct list_head list;
};
Btrfs: Make free space cache code generic So we can re-use the code to cache free inode numbers. The change is quite straightforward. Two new structures are introduced. - struct btrfs_free_space_ctl We move those variables that are used for caching free space from struct btrfs_block_group_cache to this new struct. - struct btrfs_free_space_op We do block group specific work (e.g. calculation of extents threshold) through functions registered in this struct. And then we can remove references to struct btrfs_block_group_cache. Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
2011-03-29 05:46:06 +00:00
struct btrfs_free_space_ctl {
spinlock_t tree_lock;
struct rb_root free_space_offset;
u64 free_space;
int extents_thresh;
int free_extents;
int total_bitmaps;
int unit;
u64 start;
struct btrfs_free_space_op *op;
void *private;
Btrfs: fix race between writing free space cache and trimming Trimming is completely transactionless, and the way it operates consists of hiding free space entries from a block group, perform the trim/discard and then make the free space entries visible again. Therefore while a free space entry is being trimmed, we can have free space cache writing running in parallel (as part of a transaction commit) which will miss the free space entry. This means that an unmount (or crash/reboot) after that transaction commit and mount again before another transaction starts/commits after the discard finishes, we will have some free space that won't be used again unless the free space cache is rebuilt. After the unmount, fsck (btrfsck, btrfs check) reports the issue like the following example: *** fsck.btrfs output *** checking extents checking free space cache There is no free space entry for 521764864-521781248 There is no free space entry for 521764864-1103101952 cache appears valid but isnt 29360128 Checking filesystem on /dev/sdc UUID: b4789e27-4774-4626-98e9-ae8dfbfb0fb5 found 1235681286 bytes used err is -22 (...) Another issue caused by this race is a crash while writing bitmap entries to the cache, because while the cache writeout task accesses the bitmaps, the trim task can be concurrently modifying the bitmap or worse might be freeing the bitmap. The later case results in the following crash: [55650.804460] general protection fault: 0000 [#1] SMP DEBUG_PAGEALLOC [55650.804835] Modules linked in: btrfs dm_flakey dm_mod crc32c_generic xor raid6_pq nfsd auth_rpcgss oid_registry nfs_acl nfs lockd fscache sunrpc loop parport_pc parport i2c_piix4 psmouse evdev pcspkr microcode processor i2ccore serio_raw thermal_sys button ext4 crc16 jbd2 mbcache sg sd_mod crc_t10dif sr_mod cdrom crct10dif_generic crct10dif_common ata_generic virtio_scsi floppy ata_piix libata virtio_pci virtio_ring virtio scsi_mod e1000 [last unloaded: btrfs] [55650.806169] CPU: 1 PID: 31002 Comm: btrfs-transacti Tainted: G W 3.17.0-rc5-btrfs-next-1+ #1 [55650.806493] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.7.5-0-ge51488c-20140602_164612-nilsson.home.kraxel.org 04/01/2014 [55650.806867] task: ffff8800b12f6410 ti: ffff880071538000 task.ti: ffff880071538000 [55650.807166] RIP: 0010:[<ffffffffa037cf45>] [<ffffffffa037cf45>] write_bitmap_entries+0x65/0xbb [btrfs] [55650.807514] RSP: 0018:ffff88007153bc30 EFLAGS: 00010246 [55650.807687] RAX: 000000005d1ec000 RBX: ffff8800a665df08 RCX: 0000000000000400 [55650.807885] RDX: ffff88005d1ec000 RSI: 6b6b6b6b6b6b6b6b RDI: ffff88005d1ec000 [55650.808017] RBP: ffff88007153bc58 R08: 00000000ddd51536 R09: 00000000000001e0 [55650.808017] R10: 0000000000000000 R11: 0000000000000037 R12: 6b6b6b6b6b6b6b6b [55650.808017] R13: ffff88007153bca8 R14: 6b6b6b6b6b6b6b6b R15: ffff88007153bc98 [55650.808017] FS: 0000000000000000(0000) GS:ffff88023ec80000(0000) knlGS:0000000000000000 [55650.808017] CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b [55650.808017] CR2: 0000000002273b88 CR3: 00000000b18f6000 CR4: 00000000000006e0 [55650.808017] Stack: [55650.808017] ffff88020e834e00 ffff880172d68db0 0000000000000000 ffff88019257c800 [55650.808017] ffff8801d42ea720 ffff88007153bd10 ffffffffa037d2fa ffff880224e99180 [55650.808017] ffff8801469a6188 ffff880224e99140 ffff880172d68c50 00000003000000b7 [55650.808017] Call Trace: [55650.808017] [<ffffffffa037d2fa>] __btrfs_write_out_cache+0x1ea/0x37f [btrfs] [55650.808017] [<ffffffffa037d959>] btrfs_write_out_cache+0xa1/0xd8 [btrfs] [55650.808017] [<ffffffffa033936b>] btrfs_write_dirty_block_groups+0x4b5/0x505 [btrfs] [55650.808017] [<ffffffffa03aa98e>] commit_cowonly_roots+0x15e/0x1f7 [btrfs] [55650.808017] [<ffffffff813eb9c7>] ? _raw_spin_lock+0xe/0x10 [55650.808017] [<ffffffffa0346e46>] btrfs_commit_transaction+0x411/0x882 [btrfs] [55650.808017] [<ffffffffa03432a4>] transaction_kthread+0xf2/0x1a4 [btrfs] [55650.808017] [<ffffffffa03431b2>] ? btrfs_cleanup_transaction+0x3d8/0x3d8 [btrfs] [55650.808017] [<ffffffff8105966b>] kthread+0xb7/0xbf [55650.808017] [<ffffffff810595b4>] ? __kthread_parkme+0x67/0x67 [55650.808017] [<ffffffff813ebeac>] ret_from_fork+0x7c/0xb0 [55650.808017] [<ffffffff810595b4>] ? __kthread_parkme+0x67/0x67 [55650.808017] Code: 4c 89 ef 8d 70 ff e8 d4 fc ff ff 41 8b 45 34 41 39 45 30 7d 5c 31 f6 4c 89 ef e8 80 f6 ff ff 49 8b 7d 00 4c 89 f6 b9 00 04 00 00 <f3> a5 4c 89 ef 41 8b 45 30 8d 70 ff e8 a3 fc ff ff 41 8b 45 34 [55650.808017] RIP [<ffffffffa037cf45>] write_bitmap_entries+0x65/0xbb [btrfs] [55650.808017] RSP <ffff88007153bc30> [55650.815725] ---[ end trace 1c032e96b149ff86 ]--- Fix this by serializing both tasks in such a way that cache writeout doesn't wait for the trim/discard of free space entries to finish and doesn't miss any free space entry. Signed-off-by: Filipe Manana <fdmanana@suse.com> Signed-off-by: Chris Mason <clm@fb.com>
2014-12-01 17:04:09 +00:00
struct mutex cache_writeout_mutex;
struct list_head trimming_ranges;
Btrfs: Make free space cache code generic So we can re-use the code to cache free inode numbers. The change is quite straightforward. Two new structures are introduced. - struct btrfs_free_space_ctl We move those variables that are used for caching free space from struct btrfs_block_group_cache to this new struct. - struct btrfs_free_space_op We do block group specific work (e.g. calculation of extents threshold) through functions registered in this struct. And then we can remove references to struct btrfs_block_group_cache. Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
2011-03-29 05:46:06 +00:00
};
struct btrfs_free_space_op {
void (*recalc_thresholds)(struct btrfs_free_space_ctl *ctl);
bool (*use_bitmap)(struct btrfs_free_space_ctl *ctl,
struct btrfs_free_space *info);
};
Btrfs: create special free space cache inode In order to save free space cache, we need an inode to hold the data, and we need a special item to point at the right inode for the right block group. So first, create a special item that will point to the right inode, and the number of extent entries we will have and the number of bitmaps we will have. We truncate and pre-allocate space everytime to make sure it's uptodate. This feature will be turned on as soon as you mount with -o space_cache, however it is safe to boot into old kernels, they will just generate the cache the old fashion way. When you boot back into a newer kernel we will notice that we modified and not the cache and automatically discard the cache. Signed-off-by: Josef Bacik <josef@redhat.com>
2010-06-21 18:48:16 +00:00
struct inode *lookup_free_space_inode(struct btrfs_root *root,
struct btrfs_block_group_cache
*block_group, struct btrfs_path *path);
int create_free_space_inode(struct btrfs_root *root,
struct btrfs_trans_handle *trans,
struct btrfs_block_group_cache *block_group,
struct btrfs_path *path);
Btrfs: write out free space cache This is a simple bit, just dump the free space cache out to our preallocated inode when we're writing out dirty block groups. There are a bunch of changes in inode.c in order to account for special cases. Mostly when we're doing the writeout we're holding trans_mutex, so we need to use the nolock transacation functions. Also we can't do asynchronous completions since the async thread could be blocked on already completed IO waiting for the transaction lock. This has been tested with xfstests and btrfs filesystem balance, as well as my ENOSPC tests. Thanks, Signed-off-by: Josef Bacik <josef@redhat.com>
2010-07-02 16:14:14 +00:00
Btrfs: don't use global block reservation for inode cache truncation It is very likely that there are lots of subvolumes/snapshots in the filesystem, so if we use global block reservation to do inode cache truncation, we may hog all the free space that is reserved in global rsv. So it is better that we do the free space reservation for inode cache truncation by ourselves. Cc: Tsutomu Itoh <t-itoh@jp.fujitsu.com> Signed-off-by: Miao Xie <miaox@cn.fujitsu.com> Signed-off-by: Josef Bacik <jbacik@fusionio.com>
2013-05-13 13:55:09 +00:00
int btrfs_check_trunc_cache_free_space(struct btrfs_root *root,
struct btrfs_block_rsv *rsv);
Btrfs: create special free space cache inode In order to save free space cache, we need an inode to hold the data, and we need a special item to point at the right inode for the right block group. So first, create a special item that will point to the right inode, and the number of extent entries we will have and the number of bitmaps we will have. We truncate and pre-allocate space everytime to make sure it's uptodate. This feature will be turned on as soon as you mount with -o space_cache, however it is safe to boot into old kernels, they will just generate the cache the old fashion way. When you boot back into a newer kernel we will notice that we modified and not the cache and automatically discard the cache. Signed-off-by: Josef Bacik <josef@redhat.com>
2010-06-21 18:48:16 +00:00
int btrfs_truncate_free_space_cache(struct btrfs_root *root,
struct btrfs_trans_handle *trans,
struct inode *inode);
Btrfs: load free space cache if it exists This patch actually loads the free space cache if it exists. The only thing that really changes here is that we need to cache the block group if we're going to remove an extent from it. Previously we did not do this since the caching kthread would pick it up. With the on disk cache we don't have this luxury so we need to make sure we read the on disk cache in first, and then remove the extent, that way when the extent is unpinned the free space is added to the block group. This has been tested with all sorts of things. Signed-off-by: Josef Bacik <josef@redhat.com>
2010-08-25 20:54:15 +00:00
int load_free_space_cache(struct btrfs_fs_info *fs_info,
struct btrfs_block_group_cache *block_group);
Btrfs: write out free space cache This is a simple bit, just dump the free space cache out to our preallocated inode when we're writing out dirty block groups. There are a bunch of changes in inode.c in order to account for special cases. Mostly when we're doing the writeout we're holding trans_mutex, so we need to use the nolock transacation functions. Also we can't do asynchronous completions since the async thread could be blocked on already completed IO waiting for the transaction lock. This has been tested with xfstests and btrfs filesystem balance, as well as my ENOSPC tests. Thanks, Signed-off-by: Josef Bacik <josef@redhat.com>
2010-07-02 16:14:14 +00:00
int btrfs_write_out_cache(struct btrfs_root *root,
struct btrfs_trans_handle *trans,
struct btrfs_block_group_cache *block_group,
struct btrfs_path *path);
Btrfs: Cache free inode numbers in memory Currently btrfs stores the highest objectid of the fs tree, and it always returns (highest+1) inode number when we create a file, so inode numbers won't be reclaimed when we delete files, so we'll run out of inode numbers as we keep create/delete files in 32bits machines. This fixes it, and it works similarly to how we cache free space in block cgroups. We start a kernel thread to read the file tree. By scanning inode items, we know which chunks of inode numbers are free, and we cache them in an rb-tree. Because we are searching the commit root, we have to carefully handle the cross-transaction case. The rb-tree is a hybrid extent+bitmap tree, so if we have too many small chunks of inode numbers, we'll use bitmaps. Initially we allow 16K ram of extents, and a bitmap will be used if we exceed this threshold. The extents threshold is adjusted in runtime. Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
2011-04-20 02:06:11 +00:00
Btrfs: Support reading/writing on disk free ino cache This is similar to block group caching. We dedicate a special inode in fs tree to save free ino cache. At the very first time we create/delete a file after mount, the free ino cache will be loaded from disk into memory. When the fs tree is commited, the cache will be written back to disk. To keep compatibility, we check the root generation against the generation of the special inode when loading the cache, so the loading will fail if the btrfs filesystem was mounted in an older kernel before. Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
2011-04-20 02:33:24 +00:00
struct inode *lookup_free_ino_inode(struct btrfs_root *root,
struct btrfs_path *path);
int create_free_ino_inode(struct btrfs_root *root,
struct btrfs_trans_handle *trans,
struct btrfs_path *path);
int load_free_ino_cache(struct btrfs_fs_info *fs_info,
struct btrfs_root *root);
int btrfs_write_out_ino_cache(struct btrfs_root *root,
struct btrfs_trans_handle *trans,
Btrfs: remove duplicated ino cache's inode lookup We're doing a unnecessary extra lookup of the ino cache's inode when we already have it (and holding a reference) during the process of saving the ino cache contents to disk. Therefore remove this extra lookup. Signed-off-by: Filipe David Borba Manana <fdmanana@gmail.com> Signed-off-by: Josef Bacik <jbacik@fusionio.com> Signed-off-by: Chris Mason <chris.mason@fusionio.com>
2013-09-20 13:43:28 +00:00
struct btrfs_path *path,
struct inode *inode);
Btrfs: Support reading/writing on disk free ino cache This is similar to block group caching. We dedicate a special inode in fs tree to save free ino cache. At the very first time we create/delete a file after mount, the free ino cache will be loaded from disk into memory. When the fs tree is commited, the cache will be written back to disk. To keep compatibility, we check the root generation against the generation of the special inode when loading the cache, so the loading will fail if the btrfs filesystem was mounted in an older kernel before. Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
2011-04-20 02:33:24 +00:00
Btrfs: Make free space cache code generic So we can re-use the code to cache free inode numbers. The change is quite straightforward. Two new structures are introduced. - struct btrfs_free_space_ctl We move those variables that are used for caching free space from struct btrfs_block_group_cache to this new struct. - struct btrfs_free_space_op We do block group specific work (e.g. calculation of extents threshold) through functions registered in this struct. And then we can remove references to struct btrfs_block_group_cache. Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
2011-03-29 05:46:06 +00:00
void btrfs_init_free_space_ctl(struct btrfs_block_group_cache *block_group);
Btrfs: Cache free inode numbers in memory Currently btrfs stores the highest objectid of the fs tree, and it always returns (highest+1) inode number when we create a file, so inode numbers won't be reclaimed when we delete files, so we'll run out of inode numbers as we keep create/delete files in 32bits machines. This fixes it, and it works similarly to how we cache free space in block cgroups. We start a kernel thread to read the file tree. By scanning inode items, we know which chunks of inode numbers are free, and we cache them in an rb-tree. Because we are searching the commit root, we have to carefully handle the cross-transaction case. The rb-tree is a hybrid extent+bitmap tree, so if we have too many small chunks of inode numbers, we'll use bitmaps. Initially we allow 16K ram of extents, and a bitmap will be used if we exceed this threshold. The extents threshold is adjusted in runtime. Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
2011-04-20 02:06:11 +00:00
int __btrfs_add_free_space(struct btrfs_free_space_ctl *ctl,
u64 bytenr, u64 size);
static inline int
btrfs_add_free_space(struct btrfs_block_group_cache *block_group,
u64 bytenr, u64 size)
{
return __btrfs_add_free_space(block_group->free_space_ctl,
bytenr, size);
}
Btrfs: rework allocation clustering Because btrfs is copy-on-write, we end up picking new locations for blocks very often. This makes it fairly difficult to maintain perfect read patterns over time, but we can at least do some optimizations for writes. This is done today by remembering the last place we allocated and trying to find a free space hole big enough to hold more than just one allocation. The end result is that we tend to write sequentially to the drive. This happens all the time for metadata and it happens for data when mounted -o ssd. But, the way we record it is fairly racey and it tends to fragment the free space over time because we are trying to allocate fairly large areas at once. This commit gets rid of the races by adding a free space cluster object with dedicated locking to make sure that only one process at a time is out replacing the cluster. The free space fragmentation is somewhat solved by allowing a cluster to be comprised of smaller free space extents. This part definitely adds some CPU time to the cluster allocations, but it allows the allocator to consume the small holes left behind by cow. Signed-off-by: Chris Mason <chris.mason@oracle.com>
2009-04-03 13:47:43 +00:00
int btrfs_remove_free_space(struct btrfs_block_group_cache *block_group,
u64 bytenr, u64 size);
Btrfs: Cache free inode numbers in memory Currently btrfs stores the highest objectid of the fs tree, and it always returns (highest+1) inode number when we create a file, so inode numbers won't be reclaimed when we delete files, so we'll run out of inode numbers as we keep create/delete files in 32bits machines. This fixes it, and it works similarly to how we cache free space in block cgroups. We start a kernel thread to read the file tree. By scanning inode items, we know which chunks of inode numbers are free, and we cache them in an rb-tree. Because we are searching the commit root, we have to carefully handle the cross-transaction case. The rb-tree is a hybrid extent+bitmap tree, so if we have too many small chunks of inode numbers, we'll use bitmaps. Initially we allow 16K ram of extents, and a bitmap will be used if we exceed this threshold. The extents threshold is adjusted in runtime. Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
2011-04-20 02:06:11 +00:00
void __btrfs_remove_free_space_cache(struct btrfs_free_space_ctl *ctl);
Btrfs: rework allocation clustering Because btrfs is copy-on-write, we end up picking new locations for blocks very often. This makes it fairly difficult to maintain perfect read patterns over time, but we can at least do some optimizations for writes. This is done today by remembering the last place we allocated and trying to find a free space hole big enough to hold more than just one allocation. The end result is that we tend to write sequentially to the drive. This happens all the time for metadata and it happens for data when mounted -o ssd. But, the way we record it is fairly racey and it tends to fragment the free space over time because we are trying to allocate fairly large areas at once. This commit gets rid of the races by adding a free space cluster object with dedicated locking to make sure that only one process at a time is out replacing the cluster. The free space fragmentation is somewhat solved by allowing a cluster to be comprised of smaller free space extents. This part definitely adds some CPU time to the cluster allocations, but it allows the allocator to consume the small holes left behind by cow. Signed-off-by: Chris Mason <chris.mason@oracle.com>
2009-04-03 13:47:43 +00:00
void btrfs_remove_free_space_cache(struct btrfs_block_group_cache
Btrfs: Cache free inode numbers in memory Currently btrfs stores the highest objectid of the fs tree, and it always returns (highest+1) inode number when we create a file, so inode numbers won't be reclaimed when we delete files, so we'll run out of inode numbers as we keep create/delete files in 32bits machines. This fixes it, and it works similarly to how we cache free space in block cgroups. We start a kernel thread to read the file tree. By scanning inode items, we know which chunks of inode numbers are free, and we cache them in an rb-tree. Because we are searching the commit root, we have to carefully handle the cross-transaction case. The rb-tree is a hybrid extent+bitmap tree, so if we have too many small chunks of inode numbers, we'll use bitmaps. Initially we allow 16K ram of extents, and a bitmap will be used if we exceed this threshold. The extents threshold is adjusted in runtime. Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
2011-04-20 02:06:11 +00:00
*block_group);
Btrfs: rework allocation clustering Because btrfs is copy-on-write, we end up picking new locations for blocks very often. This makes it fairly difficult to maintain perfect read patterns over time, but we can at least do some optimizations for writes. This is done today by remembering the last place we allocated and trying to find a free space hole big enough to hold more than just one allocation. The end result is that we tend to write sequentially to the drive. This happens all the time for metadata and it happens for data when mounted -o ssd. But, the way we record it is fairly racey and it tends to fragment the free space over time because we are trying to allocate fairly large areas at once. This commit gets rid of the races by adding a free space cluster object with dedicated locking to make sure that only one process at a time is out replacing the cluster. The free space fragmentation is somewhat solved by allowing a cluster to be comprised of smaller free space extents. This part definitely adds some CPU time to the cluster allocations, but it allows the allocator to consume the small holes left behind by cow. Signed-off-by: Chris Mason <chris.mason@oracle.com>
2009-04-03 13:47:43 +00:00
u64 btrfs_find_space_for_alloc(struct btrfs_block_group_cache *block_group,
Btrfs: allocate the free space by the existed max extent size when ENOSPC By the current code, if the requested size is very large, and all the extents in the free space cache are small, we will waste lots of the cpu time to cut the requested size in half and search the cache again and again until it gets down to the size the allocator can return. In fact, we can know the max extent size in the cache after the first search, so we needn't cut the size in half repeatedly, and just use the max extent size directly. This way can save lots of cpu time and make the performance grow up when there are only fragments in the free space cache. According to my test, if there are only 4KB free space extents in the fs, and the total size of those extents are 256MB, we can reduce the execute time of the following test from 5.4s to 1.4s. dd if=/dev/zero of=<testfile> bs=1MB count=1 oflag=sync Changelog v2 -> v3: - fix the problem that we skip the block group with the space which is less than we need. Changelog v1 -> v2: - address the problem that we return a wrong start position when searching the free space in a bitmap. Signed-off-by: Miao Xie <miaox@cn.fujitsu.com> Signed-off-by: Josef Bacik <jbacik@fusionio.com> Signed-off-by: Chris Mason <chris.mason@fusionio.com>
2013-09-09 05:19:42 +00:00
u64 offset, u64 bytes, u64 empty_size,
u64 *max_extent_size);
Btrfs: Cache free inode numbers in memory Currently btrfs stores the highest objectid of the fs tree, and it always returns (highest+1) inode number when we create a file, so inode numbers won't be reclaimed when we delete files, so we'll run out of inode numbers as we keep create/delete files in 32bits machines. This fixes it, and it works similarly to how we cache free space in block cgroups. We start a kernel thread to read the file tree. By scanning inode items, we know which chunks of inode numbers are free, and we cache them in an rb-tree. Because we are searching the commit root, we have to carefully handle the cross-transaction case. The rb-tree is a hybrid extent+bitmap tree, so if we have too many small chunks of inode numbers, we'll use bitmaps. Initially we allow 16K ram of extents, and a bitmap will be used if we exceed this threshold. The extents threshold is adjusted in runtime. Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
2011-04-20 02:06:11 +00:00
u64 btrfs_find_ino_for_alloc(struct btrfs_root *fs_root);
Btrfs: rework allocation clustering Because btrfs is copy-on-write, we end up picking new locations for blocks very often. This makes it fairly difficult to maintain perfect read patterns over time, but we can at least do some optimizations for writes. This is done today by remembering the last place we allocated and trying to find a free space hole big enough to hold more than just one allocation. The end result is that we tend to write sequentially to the drive. This happens all the time for metadata and it happens for data when mounted -o ssd. But, the way we record it is fairly racey and it tends to fragment the free space over time because we are trying to allocate fairly large areas at once. This commit gets rid of the races by adding a free space cluster object with dedicated locking to make sure that only one process at a time is out replacing the cluster. The free space fragmentation is somewhat solved by allowing a cluster to be comprised of smaller free space extents. This part definitely adds some CPU time to the cluster allocations, but it allows the allocator to consume the small holes left behind by cow. Signed-off-by: Chris Mason <chris.mason@oracle.com>
2009-04-03 13:47:43 +00:00
void btrfs_dump_free_space(struct btrfs_block_group_cache *block_group,
u64 bytes);
Btrfs: avoid starting a transaction in the write path I noticed while looking at a deadlock that we are always starting a transaction in cow_file_range(). This isn't really needed since we only need a transaction if we are doing an inline extent, or if the allocator needs to allocate a chunk. So push down all the transaction start stuff to be closer to where we actually need a transaction in all of these cases. This will hopefully reduce our write latency when we are committing often. Thanks, Signed-off-by: Josef Bacik <jbacik@fusionio.com> Signed-off-by: Chris Mason <chris.mason@fusionio.com>
2013-08-14 18:02:47 +00:00
int btrfs_find_space_cluster(struct btrfs_root *root,
Btrfs: rework allocation clustering Because btrfs is copy-on-write, we end up picking new locations for blocks very often. This makes it fairly difficult to maintain perfect read patterns over time, but we can at least do some optimizations for writes. This is done today by remembering the last place we allocated and trying to find a free space hole big enough to hold more than just one allocation. The end result is that we tend to write sequentially to the drive. This happens all the time for metadata and it happens for data when mounted -o ssd. But, the way we record it is fairly racey and it tends to fragment the free space over time because we are trying to allocate fairly large areas at once. This commit gets rid of the races by adding a free space cluster object with dedicated locking to make sure that only one process at a time is out replacing the cluster. The free space fragmentation is somewhat solved by allowing a cluster to be comprised of smaller free space extents. This part definitely adds some CPU time to the cluster allocations, but it allows the allocator to consume the small holes left behind by cow. Signed-off-by: Chris Mason <chris.mason@oracle.com>
2009-04-03 13:47:43 +00:00
struct btrfs_block_group_cache *block_group,
struct btrfs_free_cluster *cluster,
u64 offset, u64 bytes, u64 empty_size);
void btrfs_init_free_cluster(struct btrfs_free_cluster *cluster);
u64 btrfs_alloc_from_cluster(struct btrfs_block_group_cache *block_group,
struct btrfs_free_cluster *cluster, u64 bytes,
Btrfs: allocate the free space by the existed max extent size when ENOSPC By the current code, if the requested size is very large, and all the extents in the free space cache are small, we will waste lots of the cpu time to cut the requested size in half and search the cache again and again until it gets down to the size the allocator can return. In fact, we can know the max extent size in the cache after the first search, so we needn't cut the size in half repeatedly, and just use the max extent size directly. This way can save lots of cpu time and make the performance grow up when there are only fragments in the free space cache. According to my test, if there are only 4KB free space extents in the fs, and the total size of those extents are 256MB, we can reduce the execute time of the following test from 5.4s to 1.4s. dd if=/dev/zero of=<testfile> bs=1MB count=1 oflag=sync Changelog v2 -> v3: - fix the problem that we skip the block group with the space which is less than we need. Changelog v1 -> v2: - address the problem that we return a wrong start position when searching the free space in a bitmap. Signed-off-by: Miao Xie <miaox@cn.fujitsu.com> Signed-off-by: Josef Bacik <jbacik@fusionio.com> Signed-off-by: Chris Mason <chris.mason@fusionio.com>
2013-09-09 05:19:42 +00:00
u64 min_start, u64 *max_extent_size);
Btrfs: rework allocation clustering Because btrfs is copy-on-write, we end up picking new locations for blocks very often. This makes it fairly difficult to maintain perfect read patterns over time, but we can at least do some optimizations for writes. This is done today by remembering the last place we allocated and trying to find a free space hole big enough to hold more than just one allocation. The end result is that we tend to write sequentially to the drive. This happens all the time for metadata and it happens for data when mounted -o ssd. But, the way we record it is fairly racey and it tends to fragment the free space over time because we are trying to allocate fairly large areas at once. This commit gets rid of the races by adding a free space cluster object with dedicated locking to make sure that only one process at a time is out replacing the cluster. The free space fragmentation is somewhat solved by allowing a cluster to be comprised of smaller free space extents. This part definitely adds some CPU time to the cluster allocations, but it allows the allocator to consume the small holes left behind by cow. Signed-off-by: Chris Mason <chris.mason@oracle.com>
2009-04-03 13:47:43 +00:00
int btrfs_return_cluster_to_free_space(
struct btrfs_block_group_cache *block_group,
struct btrfs_free_cluster *cluster);
Btrfs: add btrfs_trim_fs() to handle FITRIM We take an free extent out from allocator, trim it, then put it back, but before we trim the block group, we should make sure the block group is cached, so plus a little change to make cache_block_group() run without a transaction. Signed-off-by: Li Dongyang <lidongyang@novell.com> Signed-off-by: Chris Mason <chris.mason@oracle.com>
2011-03-24 10:24:28 +00:00
int btrfs_trim_block_group(struct btrfs_block_group_cache *block_group,
u64 *trimmed, u64 start, u64 end, u64 minlen);
Btrfs: add some free space cache tests We keep hitting bugs in the tree log replay because btrfs_remove_free_space doesn't account for some corner case. So add a bunch of tests to try and fully test btrfs_remove_free_space since the only time it is called is during tree log replay. These tests all finish successfully, so as we find more of these bugs we need to add to these tests to make sure we don't regress in fixing things. I've hidden the tests behind a Kconfig option, but they take no time to run so all btrfs developers should have this turned on all the time. Thanks, Signed-off-by: Josef Bacik <jbacik@fusionio.com>
2013-03-15 13:47:08 +00:00
Btrfs: separate out tests into their own directory The plan is to have a bunch of unit tests that run when btrfs is loaded when you build with the appropriate config option. My ultimate goal is to have a test for every non-static function we have, but at first I'm going to focus on the things that cause us the most problems. To start out with this just adds a tests/ directory and moves the existing free space cache tests into that directory and sets up all of the infrastructure. Thanks, Signed-off-by: Josef Bacik <jbacik@fusionio.com> Signed-off-by: Chris Mason <chris.mason@fusionio.com>
2013-08-14 19:05:12 +00:00
/* Support functions for runnint our sanity tests */
#ifdef CONFIG_BTRFS_FS_RUN_SANITY_TESTS
int test_add_free_space_entry(struct btrfs_block_group_cache *cache,
u64 offset, u64 bytes, bool bitmap);
int test_check_exists(struct btrfs_block_group_cache *cache,
u64 offset, u64 bytes);
#endif
Btrfs: add some free space cache tests We keep hitting bugs in the tree log replay because btrfs_remove_free_space doesn't account for some corner case. So add a bunch of tests to try and fully test btrfs_remove_free_space since the only time it is called is during tree log replay. These tests all finish successfully, so as we find more of these bugs we need to add to these tests to make sure we don't regress in fixing things. I've hidden the tests behind a Kconfig option, but they take no time to run so all btrfs developers should have this turned on all the time. Thanks, Signed-off-by: Josef Bacik <jbacik@fusionio.com>
2013-03-15 13:47:08 +00:00
Btrfs: rework allocation clustering Because btrfs is copy-on-write, we end up picking new locations for blocks very often. This makes it fairly difficult to maintain perfect read patterns over time, but we can at least do some optimizations for writes. This is done today by remembering the last place we allocated and trying to find a free space hole big enough to hold more than just one allocation. The end result is that we tend to write sequentially to the drive. This happens all the time for metadata and it happens for data when mounted -o ssd. But, the way we record it is fairly racey and it tends to fragment the free space over time because we are trying to allocate fairly large areas at once. This commit gets rid of the races by adding a free space cluster object with dedicated locking to make sure that only one process at a time is out replacing the cluster. The free space fragmentation is somewhat solved by allowing a cluster to be comprised of smaller free space extents. This part definitely adds some CPU time to the cluster allocations, but it allows the allocator to consume the small holes left behind by cow. Signed-off-by: Chris Mason <chris.mason@oracle.com>
2009-04-03 13:47:43 +00:00
#endif
Reference in a new issue Copy permalink