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WSL2-Linux-Kernel
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btrfs: update btrfs_space_info's bytes_may_use timely 

This patch can fix some false ENOSPC errors, below test script can
reproduce one false ENOSPC error:
	#!/bin/bash
	dd if=/dev/zero of=fs.img bs=$((1024*1024)) count=128
	dev=$(losetup --show -f fs.img)
	mkfs.btrfs -f -M $dev
	mkdir /tmp/mntpoint
	mount $dev /tmp/mntpoint
	cd /tmp/mntpoint
	xfs_io -f -c "falloc 0 $((64*1024*1024))" testfile

Above script will fail for ENOSPC reason, but indeed fs still has free
space to satisfy this request. Please see call graph:
btrfs_fallocate()
|-> btrfs_alloc_data_chunk_ondemand()
|   bytes_may_use += 64M
|-> btrfs_prealloc_file_range()
    |-> btrfs_reserve_extent()
        |-> btrfs_add_reserved_bytes()
        |   alloc_type is RESERVE_ALLOC_NO_ACCOUNT, so it does not
        |   change bytes_may_use, and bytes_reserved += 64M. Now
        |   bytes_may_use + bytes_reserved == 128M, which is greater
        |   than btrfs_space_info's total_bytes, false enospc occurs.
        |   Note, the bytes_may_use decrease operation will be done in
        |   end of btrfs_fallocate(), which is too late.

Here is another simple case for buffered write:
                    CPU 1              |              CPU 2
                                       |
|-> cow_file_range()                   |-> __btrfs_buffered_write()
    |-> btrfs_reserve_extent()         |   |
    |                                  |   |
    |                                  |   |
    |    .....                         |   |-> btrfs_check_data_free_space()
    |                                  |
    |                                  |
    |-> extent_clear_unlock_delalloc() |

In CPU 1, btrfs_reserve_extent()->find_free_extent()->
btrfs_add_reserved_bytes() do not decrease bytes_may_use, the decrease
operation will be delayed to be done in extent_clear_unlock_delalloc().
Assume in this case, btrfs_reserve_extent() reserved 128MB data, CPU2's
btrfs_check_data_free_space() tries to reserve 100MB data space.
If
	100MB > data_sinfo->total_bytes - data_sinfo->bytes_used -
		data_sinfo->bytes_reserved - data_sinfo->bytes_pinned -
		data_sinfo->bytes_readonly - data_sinfo->bytes_may_use
btrfs_check_data_free_space() will try to allcate new data chunk or call
btrfs_start_delalloc_roots(), or commit current transaction in order to
reserve some free space, obviously a lot of work. But indeed it's not
necessary as long as decreasing bytes_may_use timely, we still have
free space, decreasing 128M from bytes_may_use.

To fix this issue, this patch chooses to update bytes_may_use for both
data and metadata in btrfs_add_reserved_bytes(). For compress path, real
extent length may not be equal to file content length, so introduce a
ram_bytes argument for btrfs_reserve_extent(), find_free_extent() and
btrfs_add_reserved_bytes(), it's becasue bytes_may_use is increased by
file content length. Then compress path can update bytes_may_use
correctly. Also now we can discard RESERVE_ALLOC_NO_ACCOUNT, RESERVE_ALLOC
and RESERVE_FREE.

As we know, usually EXTENT_DO_ACCOUNTING is used for error path. In
run_delalloc_nocow(), for inode marked as NODATACOW or extent marked as
PREALLOC, we also need to update bytes_may_use, but can not pass
EXTENT_DO_ACCOUNTING, because it also clears metadata reservation, so
here we introduce EXTENT_CLEAR_DATA_RESV flag to indicate btrfs_clear_bit_hook()
to update btrfs_space_info's bytes_may_use.

Meanwhile __btrfs_prealloc_file_range() will call
btrfs_free_reserved_data_space() internally for both sucessful and failed
path, btrfs_prealloc_file_range()'s callers does not need to call
btrfs_free_reserved_data_space() any more.

Signed-off-by: Wang Xiaoguang <wangxg.fnst@cn.fujitsu.com>
Reviewed-by: Josef Bacik <jbacik@fb.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Chris Mason <clm@fb.com>
This commit is contained in:
Wang Xiaoguang 2016-07-25 15:51:40 +08:00 коммит произвёл Chris Mason
Родитель 4824f1f412
Коммит 18513091af
7 изменённых файлов: 73 добавлений и 63 удалений
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2
fs/btrfs/ctree.h
Просмотреть файл

@ -2579,7 +2579,7 @@ int btrfs_alloc_logged_file_extent(struct btrfs_trans_handle *trans,
struct btrfs_root *root,
u64 root_objectid, u64 owner, u64 offset,
struct btrfs_key *ins);
int btrfs_reserve_extent(struct btrfs_root *root, u64 num_bytes,
int btrfs_reserve_extent(struct btrfs_root *root, u64 ram_bytes, u64 num_bytes,
u64 min_alloc_size, u64 empty_size, u64 hint_byte,
struct btrfs_key *ins, int is_data, int delalloc);
int btrfs_inc_ref(struct btrfs_trans_handle *trans, struct btrfs_root *root,

50
fs/btrfs/extent-tree.c
Просмотреть файл

@ -60,21 +60,6 @@ enum {
CHUNK_ALLOC_FORCE = 2,
};
/*
* Control how reservations are dealt with.
*
* RESERVE_FREE - freeing a reservation.
* RESERVE_ALLOC - allocating space and we need to update bytes_may_use for
* ENOSPC accounting
* RESERVE_ALLOC_NO_ACCOUNT - allocating space and we should not update
* bytes_may_use as the ENOSPC accounting is done elsewhere
*/
enum {
RESERVE_FREE = 0,
RESERVE_ALLOC = 1,
RESERVE_ALLOC_NO_ACCOUNT = 2,
};
static int update_block_group(struct btrfs_trans_handle *trans,
struct btrfs_root *root, u64 bytenr,
u64 num_bytes, int alloc);
@ -105,7 +90,7 @@ static int find_next_key(struct btrfs_path *path, int level,
static void dump_space_info(struct btrfs_space_info *info, u64 bytes,
int dump_block_groups);
static int btrfs_add_reserved_bytes(struct btrfs_block_group_cache *cache,
u64 num_bytes, int reserve, int delalloc);
u64 ram_bytes, u64 num_bytes, int delalloc);
static int btrfs_free_reserved_bytes(struct btrfs_block_group_cache *cache,
u64 num_bytes, int delalloc);
static int block_rsv_use_bytes(struct btrfs_block_rsv *block_rsv,
@ -3502,7 +3487,6 @@ again:
dcs = BTRFS_DC_SETUP;
else if (ret == -ENOSPC)
set_bit(BTRFS_TRANS_CACHE_ENOSPC, &trans->transaction->flags);
btrfs_free_reserved_data_space(inode, 0, num_pages);
out_put:
iput(inode);
@ -6500,8 +6484,9 @@ void btrfs_wait_block_group_reservations(struct btrfs_block_group_cache *bg)
/**
* btrfs_add_reserved_bytes - update the block_group and space info counters
* @cache: The cache we are manipulating
* @ram_bytes: The number of bytes of file content, and will be same to
* @num_bytes except for the compress path.
* @num_bytes: The number of bytes in question
* @reserve: One of the reservation enums
* @delalloc: The blocks are allocated for the delalloc write
*
* This is called by the allocator when it reserves space. Metadata
@ -6516,7 +6501,7 @@ void btrfs_wait_block_group_reservations(struct btrfs_block_group_cache *bg)
* succeeds.
*/
static int btrfs_add_reserved_bytes(struct btrfs_block_group_cache *cache,
u64 num_bytes, int reserve, int delalloc)
u64 ram_bytes, u64 num_bytes, int delalloc)
{
struct btrfs_space_info *space_info = cache->space_info;
int ret = 0;
@ -6528,13 +6513,11 @@ static int btrfs_add_reserved_bytes(struct btrfs_block_group_cache *cache,
} else {
cache->reserved += num_bytes;
space_info->bytes_reserved += num_bytes;
if (reserve == RESERVE_ALLOC) {
trace_btrfs_space_reservation(cache->fs_info,
"space_info", space_info->flags,
num_bytes, 0);
space_info->bytes_may_use -= num_bytes;
}
ram_bytes, 0);
space_info->bytes_may_use -= ram_bytes;
if (delalloc)
cache->delalloc_bytes += num_bytes;
}
@ -7433,7 +7416,7 @@ btrfs_release_block_group(struct btrfs_block_group_cache *cache,
* the free space extent currently.
*/
static noinline int find_free_extent(struct btrfs_root *orig_root,
u64 num_bytes, u64 empty_size,
u64 ram_bytes, u64 num_bytes, u64 empty_size,
u64 hint_byte, struct btrfs_key *ins,
u64 flags, int delalloc)
{
@ -7447,8 +7430,6 @@ static noinline int find_free_extent(struct btrfs_root *orig_root,
struct btrfs_space_info *space_info;
int loop = 0;
int index = __get_raid_index(flags);
int alloc_type = (flags & BTRFS_BLOCK_GROUP_DATA) ?
RESERVE_ALLOC_NO_ACCOUNT : RESERVE_ALLOC;
bool failed_cluster_refill = false;
bool failed_alloc = false;
bool use_cluster = true;
@ -7780,8 +7761,8 @@ checks:
search_start - offset);
BUG_ON(offset > search_start);
ret = btrfs_add_reserved_bytes(block_group, num_bytes,
alloc_type, delalloc);
ret = btrfs_add_reserved_bytes(block_group, ram_bytes,
num_bytes, delalloc);
if (ret == -EAGAIN) {
btrfs_add_free_space(block_group, offset, num_bytes);
goto loop;
@ -7953,7 +7934,7 @@ again:
up_read(&info->groups_sem);
}
int btrfs_reserve_extent(struct btrfs_root *root,
int btrfs_reserve_extent(struct btrfs_root *root, u64 ram_bytes,
u64 num_bytes, u64 min_alloc_size,
u64 empty_size, u64 hint_byte,
struct btrfs_key *ins, int is_data, int delalloc)
@ -7965,8 +7946,8 @@ int btrfs_reserve_extent(struct btrfs_root *root,
flags = btrfs_get_alloc_profile(root, is_data);
again:
WARN_ON(num_bytes < root->sectorsize);
ret = find_free_extent(root, num_bytes, empty_size, hint_byte, ins,
flags, delalloc);
ret = find_free_extent(root, ram_bytes, num_bytes, empty_size,
hint_byte, ins, flags, delalloc);
if (!ret && !is_data) {
btrfs_dec_block_group_reservations(root->fs_info,
ins->objectid);
@ -7975,6 +7956,7 @@ again:
num_bytes = min(num_bytes >> 1, ins->offset);
num_bytes = round_down(num_bytes, root->sectorsize);
num_bytes = max(num_bytes, min_alloc_size);
ram_bytes = num_bytes;
if (num_bytes == min_alloc_size)
final_tried = true;
goto again;
@ -8241,7 +8223,7 @@ int btrfs_alloc_logged_file_extent(struct btrfs_trans_handle *trans,
return -EINVAL;
ret = btrfs_add_reserved_bytes(block_group, ins->offset,
RESERVE_ALLOC_NO_ACCOUNT, 0);
ins->offset, 0);
BUG_ON(ret); /* logic error */
ret = alloc_reserved_file_extent(trans, root, 0, root_objectid,
0, owner, offset, ins, 1);
@ -8385,7 +8367,7 @@ struct extent_buffer *btrfs_alloc_tree_block(struct btrfs_trans_handle *trans,
if (IS_ERR(block_rsv))
return ERR_CAST(block_rsv);
ret = btrfs_reserve_extent(root, blocksize, blocksize,
ret = btrfs_reserve_extent(root, blocksize, blocksize, blocksize,
empty_size, hint, &ins, 0, 0);
if (ret)
goto out_unuse;

1
fs/btrfs/extent_io.h
Просмотреть файл

@ -20,6 +20,7 @@
#define EXTENT_DAMAGED (1U << 14)
#define EXTENT_NORESERVE (1U << 15)
#define EXTENT_QGROUP_RESERVED (1U << 16)
#define EXTENT_CLEAR_DATA_RESV (1U << 17)
#define EXTENT_IOBITS (EXTENT_LOCKED | EXTENT_WRITEBACK)
#define EXTENT_CTLBITS (EXTENT_DO_ACCOUNTING | EXTENT_FIRST_DELALLOC)

24
fs/btrfs/file.c
Просмотреть файл

@ -2675,6 +2675,7 @@ static long btrfs_fallocate(struct file *file, int mode,
alloc_start = round_down(offset, blocksize);
alloc_end = round_up(offset + len, blocksize);
cur_offset = alloc_start;
/* Make sure we aren't being give some crap mode */
if (mode & ~(FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE))
@ -2767,7 +2768,6 @@ static long btrfs_fallocate(struct file *file, int mode,
/* First, check if we exceed the qgroup limit */
INIT_LIST_HEAD(&reserve_list);
cur_offset = alloc_start;
while (1) {
em = btrfs_get_extent(inode, NULL, 0, cur_offset,
alloc_end - cur_offset, 0);
@ -2794,6 +2794,14 @@ static long btrfs_fallocate(struct file *file, int mode,
last_byte - cur_offset);
if (ret < 0)
break;
} else {
/*
* Do not need to reserve unwritten extent for this
* range, free reserved data space first, otherwise
* it'll result in false ENOSPC error.
*/
btrfs_free_reserved_data_space(inode, cur_offset,
last_byte - cur_offset);
}
free_extent_map(em);
cur_offset = last_byte;
@ -2811,6 +2819,9 @@ static long btrfs_fallocate(struct file *file, int mode,
range->start,
range->len, 1 << inode->i_blkbits,
offset + len, &alloc_hint);
else
btrfs_free_reserved_data_space(inode, range->start,
range->len);
list_del(&range->list);
kfree(range);
}
@ -2845,18 +2856,11 @@ out_unlock:
unlock_extent_cached(&BTRFS_I(inode)->io_tree, alloc_start, locked_end,
&cached_state, GFP_KERNEL);
out:
/*
* As we waited the extent range, the data_rsv_map must be empty
* in the range, as written data range will be released from it.
* And for prealloacted extent, it will also be released when
* its metadata is written.
* So this is completely used as cleanup.
*/
btrfs_qgroup_free_data(inode, alloc_start, alloc_end - alloc_start);
inode_unlock(inode);
/* Let go of our reservation. */
if (ret != 0)
btrfs_free_reserved_data_space(inode, alloc_start,
alloc_end - alloc_start);
alloc_end - cur_offset);
return ret;
}

3
fs/btrfs/inode-map.c
Просмотреть файл

@ -495,10 +495,9 @@ again:
ret = btrfs_prealloc_file_range_trans(inode, trans, 0, 0, prealloc,
prealloc, prealloc, &alloc_hint);
if (ret) {
btrfs_delalloc_release_space(inode, 0, prealloc);
btrfs_delalloc_release_metadata(inode, prealloc);
goto out_put;
}
btrfs_free_reserved_data_space(inode, 0, prealloc);
ret = btrfs_write_out_ino_cache(root, trans, path, inode);
out_put:

37
fs/btrfs/inode.c
Просмотреть файл

@ -566,6 +566,8 @@ cont:
PAGE_SET_WRITEBACK |
page_error_op |
PAGE_END_WRITEBACK);
btrfs_free_reserved_data_space_noquota(inode, start,
end - start + 1);
goto free_pages_out;
}
}
@ -742,7 +744,7 @@ retry:
lock_extent(io_tree, async_extent->start,
async_extent->start + async_extent->ram_size - 1);
ret = btrfs_reserve_extent(root,
ret = btrfs_reserve_extent(root, async_extent->ram_size,
async_extent->compressed_size,
async_extent->compressed_size,
0, alloc_hint, &ins, 1, 1);
@ -969,7 +971,8 @@ static noinline int cow_file_range(struct inode *inode,
EXTENT_DEFRAG, PAGE_UNLOCK |
PAGE_CLEAR_DIRTY | PAGE_SET_WRITEBACK |
PAGE_END_WRITEBACK);
btrfs_free_reserved_data_space_noquota(inode, start,
end - start + 1);
*nr_written = *nr_written +
(end - start + PAGE_SIZE) / PAGE_SIZE;
*page_started = 1;
@ -989,7 +992,7 @@ static noinline int cow_file_range(struct inode *inode,
unsigned long op;
cur_alloc_size = disk_num_bytes;
ret = btrfs_reserve_extent(root, cur_alloc_size,
ret = btrfs_reserve_extent(root, cur_alloc_size, cur_alloc_size,
root->sectorsize, 0, alloc_hint,
&ins, 1, 1);
if (ret < 0)
@ -1489,8 +1492,10 @@ out_check:
extent_clear_unlock_delalloc(inode, cur_offset,
cur_offset + num_bytes - 1,
locked_page, EXTENT_LOCKED |
EXTENT_DELALLOC, PAGE_UNLOCK |
PAGE_SET_PRIVATE2);
EXTENT_DELALLOC |
EXTENT_CLEAR_DATA_RESV,
PAGE_UNLOCK | PAGE_SET_PRIVATE2);
if (!nolock && nocow)
btrfs_end_write_no_snapshoting(root);
cur_offset = extent_end;
@ -1807,7 +1812,9 @@ static void btrfs_clear_bit_hook(struct inode *inode,
return;
if (root->root_key.objectid != BTRFS_DATA_RELOC_TREE_OBJECTID
&& do_list && !(state->state & EXTENT_NORESERVE))
&& do_list && !(state->state & EXTENT_NORESERVE)
&& (*bits & (EXTENT_DO_ACCOUNTING |
EXTENT_CLEAR_DATA_RESV)))
btrfs_free_reserved_data_space_noquota(inode,
state->start, len);
@ -7252,7 +7259,7 @@ static struct extent_map *btrfs_new_extent_direct(struct inode *inode,
int ret;
alloc_hint = get_extent_allocation_hint(inode, start, len);
ret = btrfs_reserve_extent(root, len, root->sectorsize, 0,
ret = btrfs_reserve_extent(root, len, len, root->sectorsize, 0,
alloc_hint, &ins, 1, 1);
if (ret)
return ERR_PTR(ret);
@ -7752,6 +7759,13 @@ static int btrfs_get_blocks_direct(struct inode *inode, sector_t iblock,
ret = PTR_ERR(em2);
goto unlock_err;
}
/*
* For inode marked NODATACOW or extent marked PREALLOC,
* use the existing or preallocated extent, so does not
* need to adjust btrfs_space_info's bytes_may_use.
*/
btrfs_free_reserved_data_space_noquota(inode,
start, len);
goto unlock;
}
}
@ -7786,7 +7800,6 @@ unlock:
i_size_write(inode, start + len);
adjust_dio_outstanding_extents(inode, dio_data, len);
btrfs_free_reserved_data_space(inode, start, len);
WARN_ON(dio_data->reserve < len);
dio_data->reserve -= len;
dio_data->unsubmitted_oe_range_end = start + len;
@ -10306,6 +10319,7 @@ static int __btrfs_prealloc_file_range(struct inode *inode, int mode,
u64 last_alloc = (u64)-1;
int ret = 0;
bool own_trans = true;
u64 end = start + num_bytes - 1;
if (trans)
own_trans = false;
@ -10327,8 +10341,8 @@ static int __btrfs_prealloc_file_range(struct inode *inode, int mode,
* sized chunks.
*/
cur_bytes = min(cur_bytes, last_alloc);
ret = btrfs_reserve_extent(root, cur_bytes, min_size, 0,
*alloc_hint, &ins, 1, 0);
ret = btrfs_reserve_extent(root, cur_bytes, cur_bytes,
min_size, 0, *alloc_hint, &ins, 1, 0);
if (ret) {
if (own_trans)
btrfs_end_transaction(trans, root);
@ -10414,6 +10428,9 @@ next:
if (own_trans)
btrfs_end_transaction(trans, root);
}
if (cur_offset < end)
btrfs_free_reserved_data_space(inode, cur_offset,
end - cur_offset + 1);
return ret;
}

11
fs/btrfs/relocation.c
Просмотреть файл

@ -3040,6 +3040,7 @@ int prealloc_file_extent_cluster(struct inode *inode,
int ret = 0;
u64 prealloc_start = cluster->start - offset;
u64 prealloc_end = cluster->end - offset;
u64 cur_offset;
BUG_ON(cluster->start != cluster->boundary[0]);
inode_lock(inode);
@ -3049,6 +3050,7 @@ int prealloc_file_extent_cluster(struct inode *inode,
if (ret)
goto out;
cur_offset = prealloc_start;
while (nr < cluster->nr) {
start = cluster->boundary[nr] - offset;
if (nr + 1 < cluster->nr)
@ -3058,16 +3060,21 @@ int prealloc_file_extent_cluster(struct inode *inode,
lock_extent(&BTRFS_I(inode)->io_tree, start, end);
num_bytes = end + 1 - start;
if (cur_offset < start)
btrfs_free_reserved_data_space(inode, cur_offset,
start - cur_offset);
ret = btrfs_prealloc_file_range(inode, 0, start,
num_bytes, num_bytes,
end + 1, &alloc_hint);
cur_offset = end + 1;
unlock_extent(&BTRFS_I(inode)->io_tree, start, end);
if (ret)
break;
nr++;
}
btrfs_free_reserved_data_space(inode, prealloc_start,
prealloc_end + 1 - prealloc_start);
if (cur_offset < prealloc_end)
btrfs_free_reserved_data_space(inode, cur_offset,
prealloc_end + 1 - cur_offset);
out:
inode_unlock(inode);
return ret;