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![Josef Bacik](/assets/img/avatar_default.png)
In the face of extent root corruption, or any other core fs wide root corruption we will fail to mount the file system. This makes recovery kind of a pain, because you need to fall back to userspace tools to scrape off data. Instead provide a mechanism to gracefully handle bad roots, so we can at least mount read-only and possibly recover data from the file system. Signed-off-by: Josef Bacik <josef@toxicpanda.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
542 lines
16 KiB
C
542 lines
16 KiB
C
// SPDX-License-Identifier: GPL-2.0
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#include "misc.h"
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#include "ctree.h"
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#include "block-rsv.h"
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#include "space-info.h"
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#include "transaction.h"
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#include "block-group.h"
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/*
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* HOW DO BLOCK RESERVES WORK
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*
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* Think of block_rsv's as buckets for logically grouped metadata
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* reservations. Each block_rsv has a ->size and a ->reserved. ->size is
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* how large we want our block rsv to be, ->reserved is how much space is
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* currently reserved for this block reserve.
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*
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* ->failfast exists for the truncate case, and is described below.
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*
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* NORMAL OPERATION
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*
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* -> Reserve
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* Entrance: btrfs_block_rsv_add, btrfs_block_rsv_refill
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*
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* We call into btrfs_reserve_metadata_bytes() with our bytes, which is
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* accounted for in space_info->bytes_may_use, and then add the bytes to
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* ->reserved, and ->size in the case of btrfs_block_rsv_add.
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*
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* ->size is an over-estimation of how much we may use for a particular
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* operation.
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*
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* -> Use
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* Entrance: btrfs_use_block_rsv
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*
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* When we do a btrfs_alloc_tree_block() we call into btrfs_use_block_rsv()
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* to determine the appropriate block_rsv to use, and then verify that
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* ->reserved has enough space for our tree block allocation. Once
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* successful we subtract fs_info->nodesize from ->reserved.
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*
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* -> Finish
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* Entrance: btrfs_block_rsv_release
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*
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* We are finished with our operation, subtract our individual reservation
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* from ->size, and then subtract ->size from ->reserved and free up the
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* excess if there is any.
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*
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* There is some logic here to refill the delayed refs rsv or the global rsv
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* as needed, otherwise the excess is subtracted from
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* space_info->bytes_may_use.
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*
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* TYPES OF BLOCK RESERVES
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*
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* BLOCK_RSV_TRANS, BLOCK_RSV_DELOPS, BLOCK_RSV_CHUNK
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* These behave normally, as described above, just within the confines of the
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* lifetime of their particular operation (transaction for the whole trans
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* handle lifetime, for example).
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*
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* BLOCK_RSV_GLOBAL
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* It is impossible to properly account for all the space that may be required
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* to make our extent tree updates. This block reserve acts as an overflow
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* buffer in case our delayed refs reserve does not reserve enough space to
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* update the extent tree.
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*
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* We can steal from this in some cases as well, notably on evict() or
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* truncate() in order to help users recover from ENOSPC conditions.
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*
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* BLOCK_RSV_DELALLOC
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* The individual item sizes are determined by the per-inode size
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* calculations, which are described with the delalloc code. This is pretty
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* straightforward, it's just the calculation of ->size encodes a lot of
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* different items, and thus it gets used when updating inodes, inserting file
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* extents, and inserting checksums.
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*
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* BLOCK_RSV_DELREFS
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* We keep a running tally of how many delayed refs we have on the system.
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* We assume each one of these delayed refs are going to use a full
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* reservation. We use the transaction items and pre-reserve space for every
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* operation, and use this reservation to refill any gap between ->size and
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* ->reserved that may exist.
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*
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* From there it's straightforward, removing a delayed ref means we remove its
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* count from ->size and free up reservations as necessary. Since this is
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* the most dynamic block reserve in the system, we will try to refill this
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* block reserve first with any excess returned by any other block reserve.
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*
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* BLOCK_RSV_EMPTY
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* This is the fallback block reserve to make us try to reserve space if we
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* don't have a specific bucket for this allocation. It is mostly used for
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* updating the device tree and such, since that is a separate pool we're
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* content to just reserve space from the space_info on demand.
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*
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* BLOCK_RSV_TEMP
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* This is used by things like truncate and iput. We will temporarily
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* allocate a block reserve, set it to some size, and then truncate bytes
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* until we have no space left. With ->failfast set we'll simply return
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* ENOSPC from btrfs_use_block_rsv() to signal that we need to unwind and try
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* to make a new reservation. This is because these operations are
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* unbounded, so we want to do as much work as we can, and then back off and
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* re-reserve.
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*/
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static u64 block_rsv_release_bytes(struct btrfs_fs_info *fs_info,
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struct btrfs_block_rsv *block_rsv,
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struct btrfs_block_rsv *dest, u64 num_bytes,
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u64 *qgroup_to_release_ret)
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{
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struct btrfs_space_info *space_info = block_rsv->space_info;
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u64 qgroup_to_release = 0;
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u64 ret;
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spin_lock(&block_rsv->lock);
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if (num_bytes == (u64)-1) {
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num_bytes = block_rsv->size;
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qgroup_to_release = block_rsv->qgroup_rsv_size;
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}
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block_rsv->size -= num_bytes;
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if (block_rsv->reserved >= block_rsv->size) {
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num_bytes = block_rsv->reserved - block_rsv->size;
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block_rsv->reserved = block_rsv->size;
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block_rsv->full = 1;
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} else {
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num_bytes = 0;
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}
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if (block_rsv->qgroup_rsv_reserved >= block_rsv->qgroup_rsv_size) {
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qgroup_to_release = block_rsv->qgroup_rsv_reserved -
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block_rsv->qgroup_rsv_size;
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block_rsv->qgroup_rsv_reserved = block_rsv->qgroup_rsv_size;
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} else {
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qgroup_to_release = 0;
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}
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spin_unlock(&block_rsv->lock);
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ret = num_bytes;
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if (num_bytes > 0) {
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if (dest) {
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spin_lock(&dest->lock);
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if (!dest->full) {
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u64 bytes_to_add;
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bytes_to_add = dest->size - dest->reserved;
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bytes_to_add = min(num_bytes, bytes_to_add);
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dest->reserved += bytes_to_add;
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if (dest->reserved >= dest->size)
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dest->full = 1;
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num_bytes -= bytes_to_add;
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}
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spin_unlock(&dest->lock);
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}
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if (num_bytes)
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btrfs_space_info_free_bytes_may_use(fs_info,
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space_info,
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num_bytes);
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}
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if (qgroup_to_release_ret)
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*qgroup_to_release_ret = qgroup_to_release;
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return ret;
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}
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int btrfs_block_rsv_migrate(struct btrfs_block_rsv *src,
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struct btrfs_block_rsv *dst, u64 num_bytes,
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bool update_size)
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{
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int ret;
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ret = btrfs_block_rsv_use_bytes(src, num_bytes);
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if (ret)
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return ret;
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btrfs_block_rsv_add_bytes(dst, num_bytes, update_size);
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return 0;
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}
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void btrfs_init_block_rsv(struct btrfs_block_rsv *rsv, unsigned short type)
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{
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memset(rsv, 0, sizeof(*rsv));
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spin_lock_init(&rsv->lock);
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rsv->type = type;
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}
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void btrfs_init_metadata_block_rsv(struct btrfs_fs_info *fs_info,
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struct btrfs_block_rsv *rsv,
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unsigned short type)
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{
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btrfs_init_block_rsv(rsv, type);
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rsv->space_info = btrfs_find_space_info(fs_info,
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BTRFS_BLOCK_GROUP_METADATA);
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}
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struct btrfs_block_rsv *btrfs_alloc_block_rsv(struct btrfs_fs_info *fs_info,
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unsigned short type)
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{
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struct btrfs_block_rsv *block_rsv;
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block_rsv = kmalloc(sizeof(*block_rsv), GFP_NOFS);
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if (!block_rsv)
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return NULL;
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btrfs_init_metadata_block_rsv(fs_info, block_rsv, type);
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return block_rsv;
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}
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void btrfs_free_block_rsv(struct btrfs_fs_info *fs_info,
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struct btrfs_block_rsv *rsv)
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{
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if (!rsv)
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return;
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btrfs_block_rsv_release(fs_info, rsv, (u64)-1, NULL);
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kfree(rsv);
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}
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int btrfs_block_rsv_add(struct btrfs_root *root,
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struct btrfs_block_rsv *block_rsv, u64 num_bytes,
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enum btrfs_reserve_flush_enum flush)
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{
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int ret;
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if (num_bytes == 0)
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return 0;
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ret = btrfs_reserve_metadata_bytes(root, block_rsv, num_bytes, flush);
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if (!ret)
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btrfs_block_rsv_add_bytes(block_rsv, num_bytes, true);
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return ret;
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}
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int btrfs_block_rsv_check(struct btrfs_block_rsv *block_rsv, int min_factor)
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{
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u64 num_bytes = 0;
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int ret = -ENOSPC;
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if (!block_rsv)
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return 0;
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spin_lock(&block_rsv->lock);
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num_bytes = div_factor(block_rsv->size, min_factor);
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if (block_rsv->reserved >= num_bytes)
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ret = 0;
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spin_unlock(&block_rsv->lock);
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return ret;
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}
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int btrfs_block_rsv_refill(struct btrfs_root *root,
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struct btrfs_block_rsv *block_rsv, u64 min_reserved,
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enum btrfs_reserve_flush_enum flush)
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{
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u64 num_bytes = 0;
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int ret = -ENOSPC;
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if (!block_rsv)
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return 0;
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spin_lock(&block_rsv->lock);
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num_bytes = min_reserved;
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if (block_rsv->reserved >= num_bytes)
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ret = 0;
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else
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num_bytes -= block_rsv->reserved;
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spin_unlock(&block_rsv->lock);
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if (!ret)
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return 0;
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ret = btrfs_reserve_metadata_bytes(root, block_rsv, num_bytes, flush);
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if (!ret) {
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btrfs_block_rsv_add_bytes(block_rsv, num_bytes, false);
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return 0;
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}
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return ret;
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}
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u64 btrfs_block_rsv_release(struct btrfs_fs_info *fs_info,
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struct btrfs_block_rsv *block_rsv, u64 num_bytes,
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u64 *qgroup_to_release)
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{
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struct btrfs_block_rsv *global_rsv = &fs_info->global_block_rsv;
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struct btrfs_block_rsv *delayed_rsv = &fs_info->delayed_refs_rsv;
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struct btrfs_block_rsv *target = NULL;
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/*
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* If we are the delayed_rsv then push to the global rsv, otherwise dump
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* into the delayed rsv if it is not full.
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*/
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if (block_rsv == delayed_rsv)
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target = global_rsv;
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else if (block_rsv != global_rsv && !delayed_rsv->full)
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target = delayed_rsv;
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if (target && block_rsv->space_info != target->space_info)
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target = NULL;
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return block_rsv_release_bytes(fs_info, block_rsv, target, num_bytes,
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qgroup_to_release);
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}
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int btrfs_block_rsv_use_bytes(struct btrfs_block_rsv *block_rsv, u64 num_bytes)
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{
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int ret = -ENOSPC;
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spin_lock(&block_rsv->lock);
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if (block_rsv->reserved >= num_bytes) {
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block_rsv->reserved -= num_bytes;
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if (block_rsv->reserved < block_rsv->size)
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block_rsv->full = 0;
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ret = 0;
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}
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spin_unlock(&block_rsv->lock);
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return ret;
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}
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void btrfs_block_rsv_add_bytes(struct btrfs_block_rsv *block_rsv,
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u64 num_bytes, bool update_size)
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{
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spin_lock(&block_rsv->lock);
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block_rsv->reserved += num_bytes;
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if (update_size)
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block_rsv->size += num_bytes;
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else if (block_rsv->reserved >= block_rsv->size)
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block_rsv->full = 1;
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spin_unlock(&block_rsv->lock);
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}
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int btrfs_cond_migrate_bytes(struct btrfs_fs_info *fs_info,
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struct btrfs_block_rsv *dest, u64 num_bytes,
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int min_factor)
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{
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struct btrfs_block_rsv *global_rsv = &fs_info->global_block_rsv;
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u64 min_bytes;
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if (global_rsv->space_info != dest->space_info)
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return -ENOSPC;
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spin_lock(&global_rsv->lock);
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min_bytes = div_factor(global_rsv->size, min_factor);
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if (global_rsv->reserved < min_bytes + num_bytes) {
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spin_unlock(&global_rsv->lock);
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return -ENOSPC;
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}
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global_rsv->reserved -= num_bytes;
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if (global_rsv->reserved < global_rsv->size)
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global_rsv->full = 0;
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spin_unlock(&global_rsv->lock);
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btrfs_block_rsv_add_bytes(dest, num_bytes, true);
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return 0;
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}
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void btrfs_update_global_block_rsv(struct btrfs_fs_info *fs_info)
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{
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struct btrfs_block_rsv *block_rsv = &fs_info->global_block_rsv;
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struct btrfs_space_info *sinfo = block_rsv->space_info;
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u64 num_bytes;
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unsigned min_items;
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/*
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* The global block rsv is based on the size of the extent tree, the
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* checksum tree and the root tree. If the fs is empty we want to set
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* it to a minimal amount for safety.
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*/
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num_bytes = btrfs_root_used(&fs_info->extent_root->root_item) +
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btrfs_root_used(&fs_info->csum_root->root_item) +
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btrfs_root_used(&fs_info->tree_root->root_item);
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/*
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* We at a minimum are going to modify the csum root, the tree root, and
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* the extent root.
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*/
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min_items = 3;
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/*
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* But we also want to reserve enough space so we can do the fallback
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* global reserve for an unlink, which is an additional 5 items (see the
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* comment in __unlink_start_trans for what we're modifying.)
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*
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* But we also need space for the delayed ref updates from the unlink,
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* so its 10, 5 for the actual operation, and 5 for the delayed ref
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* updates.
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*/
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min_items += 10;
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num_bytes = max_t(u64, num_bytes,
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btrfs_calc_insert_metadata_size(fs_info, min_items));
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spin_lock(&sinfo->lock);
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spin_lock(&block_rsv->lock);
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block_rsv->size = min_t(u64, num_bytes, SZ_512M);
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if (block_rsv->reserved < block_rsv->size) {
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num_bytes = block_rsv->size - block_rsv->reserved;
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btrfs_space_info_update_bytes_may_use(fs_info, sinfo,
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num_bytes);
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block_rsv->reserved = block_rsv->size;
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} else if (block_rsv->reserved > block_rsv->size) {
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num_bytes = block_rsv->reserved - block_rsv->size;
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btrfs_space_info_update_bytes_may_use(fs_info, sinfo,
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-num_bytes);
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block_rsv->reserved = block_rsv->size;
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btrfs_try_granting_tickets(fs_info, sinfo);
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}
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if (block_rsv->reserved == block_rsv->size)
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block_rsv->full = 1;
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else
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block_rsv->full = 0;
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if (block_rsv->size >= sinfo->total_bytes)
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sinfo->force_alloc = CHUNK_ALLOC_FORCE;
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spin_unlock(&block_rsv->lock);
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spin_unlock(&sinfo->lock);
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}
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void btrfs_init_global_block_rsv(struct btrfs_fs_info *fs_info)
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{
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struct btrfs_space_info *space_info;
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space_info = btrfs_find_space_info(fs_info, BTRFS_BLOCK_GROUP_SYSTEM);
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fs_info->chunk_block_rsv.space_info = space_info;
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space_info = btrfs_find_space_info(fs_info, BTRFS_BLOCK_GROUP_METADATA);
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fs_info->global_block_rsv.space_info = space_info;
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fs_info->trans_block_rsv.space_info = space_info;
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fs_info->empty_block_rsv.space_info = space_info;
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fs_info->delayed_block_rsv.space_info = space_info;
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fs_info->delayed_refs_rsv.space_info = space_info;
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/*
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* Our various recovery options can leave us with NULL roots, so check
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* here and just bail before we go dereferencing NULLs everywhere.
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*/
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if (!fs_info->extent_root || !fs_info->csum_root ||
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!fs_info->dev_root || !fs_info->chunk_root || !fs_info->tree_root)
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return;
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fs_info->extent_root->block_rsv = &fs_info->delayed_refs_rsv;
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fs_info->csum_root->block_rsv = &fs_info->delayed_refs_rsv;
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fs_info->dev_root->block_rsv = &fs_info->global_block_rsv;
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fs_info->tree_root->block_rsv = &fs_info->global_block_rsv;
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if (fs_info->quota_root)
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fs_info->quota_root->block_rsv = &fs_info->global_block_rsv;
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fs_info->chunk_root->block_rsv = &fs_info->chunk_block_rsv;
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btrfs_update_global_block_rsv(fs_info);
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}
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void btrfs_release_global_block_rsv(struct btrfs_fs_info *fs_info)
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{
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btrfs_block_rsv_release(fs_info, &fs_info->global_block_rsv, (u64)-1,
|
|
NULL);
|
|
WARN_ON(fs_info->trans_block_rsv.size > 0);
|
|
WARN_ON(fs_info->trans_block_rsv.reserved > 0);
|
|
WARN_ON(fs_info->chunk_block_rsv.size > 0);
|
|
WARN_ON(fs_info->chunk_block_rsv.reserved > 0);
|
|
WARN_ON(fs_info->delayed_block_rsv.size > 0);
|
|
WARN_ON(fs_info->delayed_block_rsv.reserved > 0);
|
|
WARN_ON(fs_info->delayed_refs_rsv.reserved > 0);
|
|
WARN_ON(fs_info->delayed_refs_rsv.size > 0);
|
|
}
|
|
|
|
static struct btrfs_block_rsv *get_block_rsv(
|
|
const struct btrfs_trans_handle *trans,
|
|
const struct btrfs_root *root)
|
|
{
|
|
struct btrfs_fs_info *fs_info = root->fs_info;
|
|
struct btrfs_block_rsv *block_rsv = NULL;
|
|
|
|
if (test_bit(BTRFS_ROOT_SHAREABLE, &root->state) ||
|
|
(root == fs_info->csum_root && trans->adding_csums) ||
|
|
(root == fs_info->uuid_root))
|
|
block_rsv = trans->block_rsv;
|
|
|
|
if (!block_rsv)
|
|
block_rsv = root->block_rsv;
|
|
|
|
if (!block_rsv)
|
|
block_rsv = &fs_info->empty_block_rsv;
|
|
|
|
return block_rsv;
|
|
}
|
|
|
|
struct btrfs_block_rsv *btrfs_use_block_rsv(struct btrfs_trans_handle *trans,
|
|
struct btrfs_root *root,
|
|
u32 blocksize)
|
|
{
|
|
struct btrfs_fs_info *fs_info = root->fs_info;
|
|
struct btrfs_block_rsv *block_rsv;
|
|
struct btrfs_block_rsv *global_rsv = &fs_info->global_block_rsv;
|
|
int ret;
|
|
bool global_updated = false;
|
|
|
|
block_rsv = get_block_rsv(trans, root);
|
|
|
|
if (unlikely(block_rsv->size == 0))
|
|
goto try_reserve;
|
|
again:
|
|
ret = btrfs_block_rsv_use_bytes(block_rsv, blocksize);
|
|
if (!ret)
|
|
return block_rsv;
|
|
|
|
if (block_rsv->failfast)
|
|
return ERR_PTR(ret);
|
|
|
|
if (block_rsv->type == BTRFS_BLOCK_RSV_GLOBAL && !global_updated) {
|
|
global_updated = true;
|
|
btrfs_update_global_block_rsv(fs_info);
|
|
goto again;
|
|
}
|
|
|
|
/*
|
|
* The global reserve still exists to save us from ourselves, so don't
|
|
* warn_on if we are short on our delayed refs reserve.
|
|
*/
|
|
if (block_rsv->type != BTRFS_BLOCK_RSV_DELREFS &&
|
|
btrfs_test_opt(fs_info, ENOSPC_DEBUG)) {
|
|
static DEFINE_RATELIMIT_STATE(_rs,
|
|
DEFAULT_RATELIMIT_INTERVAL * 10,
|
|
/*DEFAULT_RATELIMIT_BURST*/ 1);
|
|
if (__ratelimit(&_rs))
|
|
WARN(1, KERN_DEBUG
|
|
"BTRFS: block rsv %d returned %d\n",
|
|
block_rsv->type, ret);
|
|
}
|
|
try_reserve:
|
|
ret = btrfs_reserve_metadata_bytes(root, block_rsv, blocksize,
|
|
BTRFS_RESERVE_NO_FLUSH);
|
|
if (!ret)
|
|
return block_rsv;
|
|
/*
|
|
* If we couldn't reserve metadata bytes try and use some from
|
|
* the global reserve if its space type is the same as the global
|
|
* reservation.
|
|
*/
|
|
if (block_rsv->type != BTRFS_BLOCK_RSV_GLOBAL &&
|
|
block_rsv->space_info == global_rsv->space_info) {
|
|
ret = btrfs_block_rsv_use_bytes(global_rsv, blocksize);
|
|
if (!ret)
|
|
return global_rsv;
|
|
}
|
|
return ERR_PTR(ret);
|
|
}
|