481 lines
17 KiB
C
481 lines
17 KiB
C
// SPDX-License-Identifier: GPL-2.0
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#include "ctree.h"
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#include "delalloc-space.h"
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#include "block-rsv.h"
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#include "btrfs_inode.h"
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#include "space-info.h"
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#include "transaction.h"
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#include "qgroup.h"
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#include "block-group.h"
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/*
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* HOW DOES THIS WORK
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*
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* There are two stages to data reservations, one for data and one for metadata
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* to handle the new extents and checksums generated by writing data.
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*
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*
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* DATA RESERVATION
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* The general flow of the data reservation is as follows
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*
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* -> Reserve
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* We call into btrfs_reserve_data_bytes() for the user request bytes that
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* they wish to write. We make this reservation and add it to
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* space_info->bytes_may_use. We set EXTENT_DELALLOC on the inode io_tree
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* for the range and carry on if this is buffered, or follow up trying to
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* make a real allocation if we are pre-allocating or doing O_DIRECT.
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*
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* -> Use
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* At writepages()/prealloc/O_DIRECT time we will call into
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* btrfs_reserve_extent() for some part or all of this range of bytes. We
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* will make the allocation and subtract space_info->bytes_may_use by the
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* original requested length and increase the space_info->bytes_reserved by
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* the allocated length. This distinction is important because compression
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* may allocate a smaller on disk extent than we previously reserved.
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*
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* -> Allocation
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* finish_ordered_io() will insert the new file extent item for this range,
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* and then add a delayed ref update for the extent tree. Once that delayed
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* ref is written the extent size is subtracted from
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* space_info->bytes_reserved and added to space_info->bytes_used.
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*
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* Error handling
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*
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* -> By the reservation maker
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* This is the simplest case, we haven't completed our operation and we know
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* how much we reserved, we can simply call
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* btrfs_free_reserved_data_space*() and it will be removed from
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* space_info->bytes_may_use.
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*
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* -> After the reservation has been made, but before cow_file_range()
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* This is specifically for the delalloc case. You must clear
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* EXTENT_DELALLOC with the EXTENT_CLEAR_DATA_RESV bit, and the range will
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* be subtracted from space_info->bytes_may_use.
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*
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* METADATA RESERVATION
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* The general metadata reservation lifetimes are discussed elsewhere, this
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* will just focus on how it is used for delalloc space.
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*
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* We keep track of two things on a per inode bases
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*
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* ->outstanding_extents
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* This is the number of file extent items we'll need to handle all of the
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* outstanding DELALLOC space we have in this inode. We limit the maximum
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* size of an extent, so a large contiguous dirty area may require more than
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* one outstanding_extent, which is why count_max_extents() is used to
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* determine how many outstanding_extents get added.
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*
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* ->csum_bytes
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* This is essentially how many dirty bytes we have for this inode, so we
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* can calculate the number of checksum items we would have to add in order
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* to checksum our outstanding data.
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*
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* We keep a per-inode block_rsv in order to make it easier to keep track of
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* our reservation. We use btrfs_calculate_inode_block_rsv_size() to
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* calculate the current theoretical maximum reservation we would need for the
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* metadata for this inode. We call this and then adjust our reservation as
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* necessary, either by attempting to reserve more space, or freeing up excess
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* space.
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*
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* OUTSTANDING_EXTENTS HANDLING
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*
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* ->outstanding_extents is used for keeping track of how many extents we will
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* need to use for this inode, and it will fluctuate depending on where you are
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* in the life cycle of the dirty data. Consider the following normal case for
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* a completely clean inode, with a num_bytes < our maximum allowed extent size
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*
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* -> reserve
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* ->outstanding_extents += 1 (current value is 1)
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*
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* -> set_delalloc
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* ->outstanding_extents += 1 (currrent value is 2)
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*
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* -> btrfs_delalloc_release_extents()
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* ->outstanding_extents -= 1 (current value is 1)
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*
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* We must call this once we are done, as we hold our reservation for the
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* duration of our operation, and then assume set_delalloc will update the
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* counter appropriately.
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*
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* -> add ordered extent
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* ->outstanding_extents += 1 (current value is 2)
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*
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* -> btrfs_clear_delalloc_extent
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* ->outstanding_extents -= 1 (current value is 1)
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*
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* -> finish_ordered_io/btrfs_remove_ordered_extent
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* ->outstanding_extents -= 1 (current value is 0)
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*
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* Each stage is responsible for their own accounting of the extent, thus
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* making error handling and cleanup easier.
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*/
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int btrfs_alloc_data_chunk_ondemand(struct btrfs_inode *inode, u64 bytes)
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{
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struct btrfs_root *root = inode->root;
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struct btrfs_fs_info *fs_info = root->fs_info;
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enum btrfs_reserve_flush_enum flush = BTRFS_RESERVE_FLUSH_DATA;
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/* Make sure bytes are sectorsize aligned */
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bytes = ALIGN(bytes, fs_info->sectorsize);
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if (btrfs_is_free_space_inode(inode))
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flush = BTRFS_RESERVE_FLUSH_FREE_SPACE_INODE;
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return btrfs_reserve_data_bytes(fs_info, bytes, flush);
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}
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int btrfs_check_data_free_space(struct btrfs_inode *inode,
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struct extent_changeset **reserved, u64 start, u64 len)
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{
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struct btrfs_fs_info *fs_info = inode->root->fs_info;
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int ret;
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/* align the range */
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len = round_up(start + len, fs_info->sectorsize) -
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round_down(start, fs_info->sectorsize);
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start = round_down(start, fs_info->sectorsize);
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ret = btrfs_alloc_data_chunk_ondemand(inode, len);
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if (ret < 0)
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return ret;
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/* Use new btrfs_qgroup_reserve_data to reserve precious data space. */
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ret = btrfs_qgroup_reserve_data(inode, reserved, start, len);
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if (ret < 0)
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btrfs_free_reserved_data_space_noquota(fs_info, len);
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else
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ret = 0;
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return ret;
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}
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/*
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* Called if we need to clear a data reservation for this inode
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* Normally in a error case.
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*
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* This one will *NOT* use accurate qgroup reserved space API, just for case
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* which we can't sleep and is sure it won't affect qgroup reserved space.
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* Like clear_bit_hook().
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*/
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void btrfs_free_reserved_data_space_noquota(struct btrfs_fs_info *fs_info,
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u64 len)
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{
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struct btrfs_space_info *data_sinfo;
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ASSERT(IS_ALIGNED(len, fs_info->sectorsize));
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data_sinfo = fs_info->data_sinfo;
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btrfs_space_info_free_bytes_may_use(fs_info, data_sinfo, len);
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}
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/*
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* Called if we need to clear a data reservation for this inode
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* Normally in a error case.
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*
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* This one will handle the per-inode data rsv map for accurate reserved
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* space framework.
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*/
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void btrfs_free_reserved_data_space(struct btrfs_inode *inode,
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struct extent_changeset *reserved, u64 start, u64 len)
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{
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struct btrfs_fs_info *fs_info = inode->root->fs_info;
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/* Make sure the range is aligned to sectorsize */
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len = round_up(start + len, fs_info->sectorsize) -
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round_down(start, fs_info->sectorsize);
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start = round_down(start, fs_info->sectorsize);
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btrfs_free_reserved_data_space_noquota(fs_info, len);
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btrfs_qgroup_free_data(inode, reserved, start, len);
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}
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/**
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* Release any excessive reservation
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*
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* @inode: the inode we need to release from
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* @qgroup_free: free or convert qgroup meta. Unlike normal operation, qgroup
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* meta reservation needs to know if we are freeing qgroup
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* reservation or just converting it into per-trans. Normally
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* @qgroup_free is true for error handling, and false for normal
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* release.
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*
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* This is the same as btrfs_block_rsv_release, except that it handles the
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* tracepoint for the reservation.
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*/
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static void btrfs_inode_rsv_release(struct btrfs_inode *inode, bool qgroup_free)
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{
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struct btrfs_fs_info *fs_info = inode->root->fs_info;
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struct btrfs_block_rsv *block_rsv = &inode->block_rsv;
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u64 released = 0;
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u64 qgroup_to_release = 0;
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/*
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* Since we statically set the block_rsv->size we just want to say we
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* are releasing 0 bytes, and then we'll just get the reservation over
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* the size free'd.
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*/
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released = btrfs_block_rsv_release(fs_info, block_rsv, 0,
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&qgroup_to_release);
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if (released > 0)
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trace_btrfs_space_reservation(fs_info, "delalloc",
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btrfs_ino(inode), released, 0);
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if (qgroup_free)
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btrfs_qgroup_free_meta_prealloc(inode->root, qgroup_to_release);
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else
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btrfs_qgroup_convert_reserved_meta(inode->root,
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qgroup_to_release);
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}
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static void btrfs_calculate_inode_block_rsv_size(struct btrfs_fs_info *fs_info,
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struct btrfs_inode *inode)
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{
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struct btrfs_block_rsv *block_rsv = &inode->block_rsv;
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u64 reserve_size = 0;
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u64 qgroup_rsv_size = 0;
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u64 csum_leaves;
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unsigned outstanding_extents;
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lockdep_assert_held(&inode->lock);
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outstanding_extents = inode->outstanding_extents;
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/*
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* Insert size for the number of outstanding extents, 1 normal size for
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* updating the inode.
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*/
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if (outstanding_extents) {
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reserve_size = btrfs_calc_insert_metadata_size(fs_info,
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outstanding_extents);
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reserve_size += btrfs_calc_metadata_size(fs_info, 1);
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}
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csum_leaves = btrfs_csum_bytes_to_leaves(fs_info,
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inode->csum_bytes);
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reserve_size += btrfs_calc_insert_metadata_size(fs_info,
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csum_leaves);
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/*
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* For qgroup rsv, the calculation is very simple:
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* account one nodesize for each outstanding extent
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*
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* This is overestimating in most cases.
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*/
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qgroup_rsv_size = (u64)outstanding_extents * fs_info->nodesize;
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spin_lock(&block_rsv->lock);
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block_rsv->size = reserve_size;
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block_rsv->qgroup_rsv_size = qgroup_rsv_size;
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spin_unlock(&block_rsv->lock);
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}
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static void calc_inode_reservations(struct btrfs_fs_info *fs_info,
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u64 num_bytes, u64 *meta_reserve,
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u64 *qgroup_reserve)
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{
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u64 nr_extents = count_max_extents(num_bytes);
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u64 csum_leaves = btrfs_csum_bytes_to_leaves(fs_info, num_bytes);
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u64 inode_update = btrfs_calc_metadata_size(fs_info, 1);
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*meta_reserve = btrfs_calc_insert_metadata_size(fs_info,
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nr_extents + csum_leaves);
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/*
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* finish_ordered_io has to update the inode, so add the space required
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* for an inode update.
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*/
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*meta_reserve += inode_update;
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*qgroup_reserve = nr_extents * fs_info->nodesize;
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}
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int btrfs_delalloc_reserve_metadata(struct btrfs_inode *inode, u64 num_bytes)
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{
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struct btrfs_root *root = inode->root;
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struct btrfs_fs_info *fs_info = root->fs_info;
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struct btrfs_block_rsv *block_rsv = &inode->block_rsv;
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u64 meta_reserve, qgroup_reserve;
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unsigned nr_extents;
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enum btrfs_reserve_flush_enum flush = BTRFS_RESERVE_FLUSH_ALL;
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int ret = 0;
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/*
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* If we are a free space inode we need to not flush since we will be in
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* the middle of a transaction commit. We also don't need the delalloc
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* mutex since we won't race with anybody. We need this mostly to make
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* lockdep shut its filthy mouth.
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*
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* If we have a transaction open (can happen if we call truncate_block
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* from truncate), then we need FLUSH_LIMIT so we don't deadlock.
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*/
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if (btrfs_is_free_space_inode(inode)) {
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flush = BTRFS_RESERVE_NO_FLUSH;
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} else {
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if (current->journal_info)
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flush = BTRFS_RESERVE_FLUSH_LIMIT;
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if (btrfs_transaction_in_commit(fs_info))
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schedule_timeout(1);
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}
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num_bytes = ALIGN(num_bytes, fs_info->sectorsize);
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/*
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* We always want to do it this way, every other way is wrong and ends
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* in tears. Pre-reserving the amount we are going to add will always
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* be the right way, because otherwise if we have enough parallelism we
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* could end up with thousands of inodes all holding little bits of
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* reservations they were able to make previously and the only way to
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* reclaim that space is to ENOSPC out the operations and clear
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* everything out and try again, which is bad. This way we just
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* over-reserve slightly, and clean up the mess when we are done.
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*/
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calc_inode_reservations(fs_info, num_bytes, &meta_reserve,
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&qgroup_reserve);
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ret = btrfs_qgroup_reserve_meta_prealloc(root, qgroup_reserve, true);
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if (ret)
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return ret;
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ret = btrfs_reserve_metadata_bytes(root, block_rsv, meta_reserve, flush);
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if (ret) {
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btrfs_qgroup_free_meta_prealloc(root, qgroup_reserve);
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return ret;
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}
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/*
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* Now we need to update our outstanding extents and csum bytes _first_
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* and then add the reservation to the block_rsv. This keeps us from
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* racing with an ordered completion or some such that would think it
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* needs to free the reservation we just made.
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*/
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spin_lock(&inode->lock);
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nr_extents = count_max_extents(num_bytes);
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btrfs_mod_outstanding_extents(inode, nr_extents);
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inode->csum_bytes += num_bytes;
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btrfs_calculate_inode_block_rsv_size(fs_info, inode);
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spin_unlock(&inode->lock);
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/* Now we can safely add our space to our block rsv */
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btrfs_block_rsv_add_bytes(block_rsv, meta_reserve, false);
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trace_btrfs_space_reservation(root->fs_info, "delalloc",
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btrfs_ino(inode), meta_reserve, 1);
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spin_lock(&block_rsv->lock);
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block_rsv->qgroup_rsv_reserved += qgroup_reserve;
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spin_unlock(&block_rsv->lock);
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return 0;
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}
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/**
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* Release a metadata reservation for an inode
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*
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* @inode: the inode to release the reservation for.
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* @num_bytes: the number of bytes we are releasing.
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* @qgroup_free: free qgroup reservation or convert it to per-trans reservation
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*
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* This will release the metadata reservation for an inode. This can be called
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* once we complete IO for a given set of bytes to release their metadata
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* reservations, or on error for the same reason.
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*/
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void btrfs_delalloc_release_metadata(struct btrfs_inode *inode, u64 num_bytes,
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bool qgroup_free)
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{
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struct btrfs_fs_info *fs_info = inode->root->fs_info;
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num_bytes = ALIGN(num_bytes, fs_info->sectorsize);
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spin_lock(&inode->lock);
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inode->csum_bytes -= num_bytes;
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btrfs_calculate_inode_block_rsv_size(fs_info, inode);
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spin_unlock(&inode->lock);
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if (btrfs_is_testing(fs_info))
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return;
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btrfs_inode_rsv_release(inode, qgroup_free);
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}
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/**
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* btrfs_delalloc_release_extents - release our outstanding_extents
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* @inode: the inode to balance the reservation for.
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* @num_bytes: the number of bytes we originally reserved with
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*
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* When we reserve space we increase outstanding_extents for the extents we may
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* add. Once we've set the range as delalloc or created our ordered extents we
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* have outstanding_extents to track the real usage, so we use this to free our
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* temporarily tracked outstanding_extents. This _must_ be used in conjunction
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* with btrfs_delalloc_reserve_metadata.
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*/
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void btrfs_delalloc_release_extents(struct btrfs_inode *inode, u64 num_bytes)
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{
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struct btrfs_fs_info *fs_info = inode->root->fs_info;
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unsigned num_extents;
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spin_lock(&inode->lock);
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num_extents = count_max_extents(num_bytes);
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btrfs_mod_outstanding_extents(inode, -num_extents);
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btrfs_calculate_inode_block_rsv_size(fs_info, inode);
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spin_unlock(&inode->lock);
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if (btrfs_is_testing(fs_info))
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return;
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btrfs_inode_rsv_release(inode, true);
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}
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/**
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* btrfs_delalloc_reserve_space - reserve data and metadata space for
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* delalloc
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* @inode: inode we're writing to
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* @start: start range we are writing to
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* @len: how long the range we are writing to
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* @reserved: mandatory parameter, record actually reserved qgroup ranges of
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* current reservation.
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*
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* This will do the following things
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*
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* - reserve space in data space info for num bytes
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* and reserve precious corresponding qgroup space
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* (Done in check_data_free_space)
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*
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* - reserve space for metadata space, based on the number of outstanding
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* extents and how much csums will be needed
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* also reserve metadata space in a per root over-reserve method.
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* - add to the inodes->delalloc_bytes
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* - add it to the fs_info's delalloc inodes list.
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* (Above 3 all done in delalloc_reserve_metadata)
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*
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* Return 0 for success
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* Return <0 for error(-ENOSPC or -EQUOT)
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*/
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int btrfs_delalloc_reserve_space(struct btrfs_inode *inode,
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struct extent_changeset **reserved, u64 start, u64 len)
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{
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int ret;
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ret = btrfs_check_data_free_space(inode, reserved, start, len);
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if (ret < 0)
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return ret;
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ret = btrfs_delalloc_reserve_metadata(inode, len);
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if (ret < 0)
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btrfs_free_reserved_data_space(inode, *reserved, start, len);
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return ret;
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}
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/**
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* Release data and metadata space for delalloc
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*
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* @inode: inode we're releasing space for
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* @reserved: list of changed/reserved ranges
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* @start: start position of the space already reserved
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* @len: length of the space already reserved
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* @qgroup_free: should qgroup reserved-space also be freed
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*
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* This function will release the metadata space that was not used and will
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* decrement ->delalloc_bytes and remove it from the fs_info delalloc_inodes
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* list if there are no delalloc bytes left.
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* Also it will handle the qgroup reserved space.
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*/
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void btrfs_delalloc_release_space(struct btrfs_inode *inode,
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struct extent_changeset *reserved,
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u64 start, u64 len, bool qgroup_free)
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{
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btrfs_delalloc_release_metadata(inode, len, qgroup_free);
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btrfs_free_reserved_data_space(inode, reserved, start, len);
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}
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