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-rw-r--r--fs/btrfs/delalloc-space.c493
1 files changed, 493 insertions, 0 deletions
diff --git a/fs/btrfs/delalloc-space.c b/fs/btrfs/delalloc-space.c
new file mode 100644
index 000000000..f2bc5563c
--- /dev/null
+++ b/fs/btrfs/delalloc-space.c
@@ -0,0 +1,493 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include "ctree.h"
+#include "delalloc-space.h"
+#include "block-rsv.h"
+#include "btrfs_inode.h"
+#include "space-info.h"
+#include "transaction.h"
+#include "qgroup.h"
+#include "block-group.h"
+
+/*
+ * HOW DOES THIS WORK
+ *
+ * There are two stages to data reservations, one for data and one for metadata
+ * to handle the new extents and checksums generated by writing data.
+ *
+ *
+ * DATA RESERVATION
+ * The general flow of the data reservation is as follows
+ *
+ * -> Reserve
+ * We call into btrfs_reserve_data_bytes() for the user request bytes that
+ * they wish to write. We make this reservation and add it to
+ * space_info->bytes_may_use. We set EXTENT_DELALLOC on the inode io_tree
+ * for the range and carry on if this is buffered, or follow up trying to
+ * make a real allocation if we are pre-allocating or doing O_DIRECT.
+ *
+ * -> Use
+ * At writepages()/prealloc/O_DIRECT time we will call into
+ * btrfs_reserve_extent() for some part or all of this range of bytes. We
+ * will make the allocation and subtract space_info->bytes_may_use by the
+ * original requested length and increase the space_info->bytes_reserved by
+ * the allocated length. This distinction is important because compression
+ * may allocate a smaller on disk extent than we previously reserved.
+ *
+ * -> Allocation
+ * finish_ordered_io() will insert the new file extent item for this range,
+ * and then add a delayed ref update for the extent tree. Once that delayed
+ * ref is written the extent size is subtracted from
+ * space_info->bytes_reserved and added to space_info->bytes_used.
+ *
+ * Error handling
+ *
+ * -> By the reservation maker
+ * This is the simplest case, we haven't completed our operation and we know
+ * how much we reserved, we can simply call
+ * btrfs_free_reserved_data_space*() and it will be removed from
+ * space_info->bytes_may_use.
+ *
+ * -> After the reservation has been made, but before cow_file_range()
+ * This is specifically for the delalloc case. You must clear
+ * EXTENT_DELALLOC with the EXTENT_CLEAR_DATA_RESV bit, and the range will
+ * be subtracted from space_info->bytes_may_use.
+ *
+ * METADATA RESERVATION
+ * The general metadata reservation lifetimes are discussed elsewhere, this
+ * will just focus on how it is used for delalloc space.
+ *
+ * We keep track of two things on a per inode bases
+ *
+ * ->outstanding_extents
+ * This is the number of file extent items we'll need to handle all of the
+ * outstanding DELALLOC space we have in this inode. We limit the maximum
+ * size of an extent, so a large contiguous dirty area may require more than
+ * one outstanding_extent, which is why count_max_extents() is used to
+ * determine how many outstanding_extents get added.
+ *
+ * ->csum_bytes
+ * This is essentially how many dirty bytes we have for this inode, so we
+ * can calculate the number of checksum items we would have to add in order
+ * to checksum our outstanding data.
+ *
+ * We keep a per-inode block_rsv in order to make it easier to keep track of
+ * our reservation. We use btrfs_calculate_inode_block_rsv_size() to
+ * calculate the current theoretical maximum reservation we would need for the
+ * metadata for this inode. We call this and then adjust our reservation as
+ * necessary, either by attempting to reserve more space, or freeing up excess
+ * space.
+ *
+ * OUTSTANDING_EXTENTS HANDLING
+ *
+ * ->outstanding_extents is used for keeping track of how many extents we will
+ * need to use for this inode, and it will fluctuate depending on where you are
+ * in the life cycle of the dirty data. Consider the following normal case for
+ * a completely clean inode, with a num_bytes < our maximum allowed extent size
+ *
+ * -> reserve
+ * ->outstanding_extents += 1 (current value is 1)
+ *
+ * -> set_delalloc
+ * ->outstanding_extents += 1 (current value is 2)
+ *
+ * -> btrfs_delalloc_release_extents()
+ * ->outstanding_extents -= 1 (current value is 1)
+ *
+ * We must call this once we are done, as we hold our reservation for the
+ * duration of our operation, and then assume set_delalloc will update the
+ * counter appropriately.
+ *
+ * -> add ordered extent
+ * ->outstanding_extents += 1 (current value is 2)
+ *
+ * -> btrfs_clear_delalloc_extent
+ * ->outstanding_extents -= 1 (current value is 1)
+ *
+ * -> finish_ordered_io/btrfs_remove_ordered_extent
+ * ->outstanding_extents -= 1 (current value is 0)
+ *
+ * Each stage is responsible for their own accounting of the extent, thus
+ * making error handling and cleanup easier.
+ */
+
+int btrfs_alloc_data_chunk_ondemand(struct btrfs_inode *inode, u64 bytes)
+{
+ struct btrfs_root *root = inode->root;
+ struct btrfs_fs_info *fs_info = root->fs_info;
+ enum btrfs_reserve_flush_enum flush = BTRFS_RESERVE_FLUSH_DATA;
+
+ /* Make sure bytes are sectorsize aligned */
+ bytes = ALIGN(bytes, fs_info->sectorsize);
+
+ if (btrfs_is_free_space_inode(inode))
+ flush = BTRFS_RESERVE_FLUSH_FREE_SPACE_INODE;
+
+ return btrfs_reserve_data_bytes(fs_info, bytes, flush);
+}
+
+int btrfs_check_data_free_space(struct btrfs_inode *inode,
+ struct extent_changeset **reserved, u64 start,
+ u64 len, bool noflush)
+{
+ struct btrfs_fs_info *fs_info = inode->root->fs_info;
+ enum btrfs_reserve_flush_enum flush = BTRFS_RESERVE_FLUSH_DATA;
+ int ret;
+
+ /* align the range */
+ len = round_up(start + len, fs_info->sectorsize) -
+ round_down(start, fs_info->sectorsize);
+ start = round_down(start, fs_info->sectorsize);
+
+ if (noflush)
+ flush = BTRFS_RESERVE_NO_FLUSH;
+ else if (btrfs_is_free_space_inode(inode))
+ flush = BTRFS_RESERVE_FLUSH_FREE_SPACE_INODE;
+
+ ret = btrfs_reserve_data_bytes(fs_info, len, flush);
+ if (ret < 0)
+ return ret;
+
+ /* Use new btrfs_qgroup_reserve_data to reserve precious data space. */
+ ret = btrfs_qgroup_reserve_data(inode, reserved, start, len);
+ if (ret < 0) {
+ btrfs_free_reserved_data_space_noquota(fs_info, len);
+ extent_changeset_free(*reserved);
+ *reserved = NULL;
+ } else {
+ ret = 0;
+ }
+ return ret;
+}
+
+/*
+ * Called if we need to clear a data reservation for this inode
+ * Normally in a error case.
+ *
+ * This one will *NOT* use accurate qgroup reserved space API, just for case
+ * which we can't sleep and is sure it won't affect qgroup reserved space.
+ * Like clear_bit_hook().
+ */
+void btrfs_free_reserved_data_space_noquota(struct btrfs_fs_info *fs_info,
+ u64 len)
+{
+ struct btrfs_space_info *data_sinfo;
+
+ ASSERT(IS_ALIGNED(len, fs_info->sectorsize));
+
+ data_sinfo = fs_info->data_sinfo;
+ btrfs_space_info_free_bytes_may_use(fs_info, data_sinfo, len);
+}
+
+/*
+ * Called if we need to clear a data reservation for this inode
+ * Normally in a error case.
+ *
+ * This one will handle the per-inode data rsv map for accurate reserved
+ * space framework.
+ */
+void btrfs_free_reserved_data_space(struct btrfs_inode *inode,
+ struct extent_changeset *reserved, u64 start, u64 len)
+{
+ struct btrfs_fs_info *fs_info = inode->root->fs_info;
+
+ /* Make sure the range is aligned to sectorsize */
+ len = round_up(start + len, fs_info->sectorsize) -
+ round_down(start, fs_info->sectorsize);
+ start = round_down(start, fs_info->sectorsize);
+
+ btrfs_free_reserved_data_space_noquota(fs_info, len);
+ btrfs_qgroup_free_data(inode, reserved, start, len, NULL);
+}
+
+/**
+ * Release any excessive reservation
+ *
+ * @inode: the inode we need to release from
+ * @qgroup_free: free or convert qgroup meta. Unlike normal operation, qgroup
+ * meta reservation needs to know if we are freeing qgroup
+ * reservation or just converting it into per-trans. Normally
+ * @qgroup_free is true for error handling, and false for normal
+ * release.
+ *
+ * This is the same as btrfs_block_rsv_release, except that it handles the
+ * tracepoint for the reservation.
+ */
+static void btrfs_inode_rsv_release(struct btrfs_inode *inode, bool qgroup_free)
+{
+ struct btrfs_fs_info *fs_info = inode->root->fs_info;
+ struct btrfs_block_rsv *block_rsv = &inode->block_rsv;
+ u64 released = 0;
+ u64 qgroup_to_release = 0;
+
+ /*
+ * Since we statically set the block_rsv->size we just want to say we
+ * are releasing 0 bytes, and then we'll just get the reservation over
+ * the size free'd.
+ */
+ released = btrfs_block_rsv_release(fs_info, block_rsv, 0,
+ &qgroup_to_release);
+ if (released > 0)
+ trace_btrfs_space_reservation(fs_info, "delalloc",
+ btrfs_ino(inode), released, 0);
+ if (qgroup_free)
+ btrfs_qgroup_free_meta_prealloc(inode->root, qgroup_to_release);
+ else
+ btrfs_qgroup_convert_reserved_meta(inode->root,
+ qgroup_to_release);
+}
+
+static void btrfs_calculate_inode_block_rsv_size(struct btrfs_fs_info *fs_info,
+ struct btrfs_inode *inode)
+{
+ struct btrfs_block_rsv *block_rsv = &inode->block_rsv;
+ u64 reserve_size = 0;
+ u64 qgroup_rsv_size = 0;
+ u64 csum_leaves;
+ unsigned outstanding_extents;
+
+ lockdep_assert_held(&inode->lock);
+ outstanding_extents = inode->outstanding_extents;
+
+ /*
+ * Insert size for the number of outstanding extents, 1 normal size for
+ * updating the inode.
+ */
+ if (outstanding_extents) {
+ reserve_size = btrfs_calc_insert_metadata_size(fs_info,
+ outstanding_extents);
+ reserve_size += btrfs_calc_metadata_size(fs_info, 1);
+ }
+ csum_leaves = btrfs_csum_bytes_to_leaves(fs_info,
+ inode->csum_bytes);
+ reserve_size += btrfs_calc_insert_metadata_size(fs_info,
+ csum_leaves);
+ /*
+ * For qgroup rsv, the calculation is very simple:
+ * account one nodesize for each outstanding extent
+ *
+ * This is overestimating in most cases.
+ */
+ qgroup_rsv_size = (u64)outstanding_extents * fs_info->nodesize;
+
+ spin_lock(&block_rsv->lock);
+ block_rsv->size = reserve_size;
+ block_rsv->qgroup_rsv_size = qgroup_rsv_size;
+ spin_unlock(&block_rsv->lock);
+}
+
+static void calc_inode_reservations(struct btrfs_fs_info *fs_info,
+ u64 num_bytes, u64 disk_num_bytes,
+ u64 *meta_reserve, u64 *qgroup_reserve)
+{
+ u64 nr_extents = count_max_extents(fs_info, num_bytes);
+ u64 csum_leaves = btrfs_csum_bytes_to_leaves(fs_info, disk_num_bytes);
+ u64 inode_update = btrfs_calc_metadata_size(fs_info, 1);
+
+ *meta_reserve = btrfs_calc_insert_metadata_size(fs_info,
+ nr_extents + csum_leaves);
+
+ /*
+ * finish_ordered_io has to update the inode, so add the space required
+ * for an inode update.
+ */
+ *meta_reserve += inode_update;
+ *qgroup_reserve = nr_extents * fs_info->nodesize;
+}
+
+int btrfs_delalloc_reserve_metadata(struct btrfs_inode *inode, u64 num_bytes,
+ u64 disk_num_bytes, bool noflush)
+{
+ struct btrfs_root *root = inode->root;
+ struct btrfs_fs_info *fs_info = root->fs_info;
+ struct btrfs_block_rsv *block_rsv = &inode->block_rsv;
+ u64 meta_reserve, qgroup_reserve;
+ unsigned nr_extents;
+ enum btrfs_reserve_flush_enum flush = BTRFS_RESERVE_FLUSH_ALL;
+ int ret = 0;
+
+ /*
+ * If we are a free space inode we need to not flush since we will be in
+ * the middle of a transaction commit. We also don't need the delalloc
+ * mutex since we won't race with anybody. We need this mostly to make
+ * lockdep shut its filthy mouth.
+ *
+ * If we have a transaction open (can happen if we call truncate_block
+ * from truncate), then we need FLUSH_LIMIT so we don't deadlock.
+ */
+ if (noflush || btrfs_is_free_space_inode(inode)) {
+ flush = BTRFS_RESERVE_NO_FLUSH;
+ } else {
+ if (current->journal_info)
+ flush = BTRFS_RESERVE_FLUSH_LIMIT;
+ }
+
+ num_bytes = ALIGN(num_bytes, fs_info->sectorsize);
+ disk_num_bytes = ALIGN(disk_num_bytes, fs_info->sectorsize);
+
+ /*
+ * We always want to do it this way, every other way is wrong and ends
+ * in tears. Pre-reserving the amount we are going to add will always
+ * be the right way, because otherwise if we have enough parallelism we
+ * could end up with thousands of inodes all holding little bits of
+ * reservations they were able to make previously and the only way to
+ * reclaim that space is to ENOSPC out the operations and clear
+ * everything out and try again, which is bad. This way we just
+ * over-reserve slightly, and clean up the mess when we are done.
+ */
+ calc_inode_reservations(fs_info, num_bytes, disk_num_bytes,
+ &meta_reserve, &qgroup_reserve);
+ ret = btrfs_qgroup_reserve_meta_prealloc(root, qgroup_reserve, true,
+ noflush);
+ if (ret)
+ return ret;
+ ret = btrfs_reserve_metadata_bytes(fs_info, block_rsv, meta_reserve, flush);
+ if (ret) {
+ btrfs_qgroup_free_meta_prealloc(root, qgroup_reserve);
+ return ret;
+ }
+
+ /*
+ * Now we need to update our outstanding extents and csum bytes _first_
+ * and then add the reservation to the block_rsv. This keeps us from
+ * racing with an ordered completion or some such that would think it
+ * needs to free the reservation we just made.
+ */
+ spin_lock(&inode->lock);
+ nr_extents = count_max_extents(fs_info, num_bytes);
+ btrfs_mod_outstanding_extents(inode, nr_extents);
+ inode->csum_bytes += disk_num_bytes;
+ btrfs_calculate_inode_block_rsv_size(fs_info, inode);
+ spin_unlock(&inode->lock);
+
+ /* Now we can safely add our space to our block rsv */
+ btrfs_block_rsv_add_bytes(block_rsv, meta_reserve, false);
+ trace_btrfs_space_reservation(root->fs_info, "delalloc",
+ btrfs_ino(inode), meta_reserve, 1);
+
+ spin_lock(&block_rsv->lock);
+ block_rsv->qgroup_rsv_reserved += qgroup_reserve;
+ spin_unlock(&block_rsv->lock);
+
+ return 0;
+}
+
+/**
+ * Release a metadata reservation for an inode
+ *
+ * @inode: the inode to release the reservation for.
+ * @num_bytes: the number of bytes we are releasing.
+ * @qgroup_free: free qgroup reservation or convert it to per-trans reservation
+ *
+ * This will release the metadata reservation for an inode. This can be called
+ * once we complete IO for a given set of bytes to release their metadata
+ * reservations, or on error for the same reason.
+ */
+void btrfs_delalloc_release_metadata(struct btrfs_inode *inode, u64 num_bytes,
+ bool qgroup_free)
+{
+ struct btrfs_fs_info *fs_info = inode->root->fs_info;
+
+ num_bytes = ALIGN(num_bytes, fs_info->sectorsize);
+ spin_lock(&inode->lock);
+ inode->csum_bytes -= num_bytes;
+ btrfs_calculate_inode_block_rsv_size(fs_info, inode);
+ spin_unlock(&inode->lock);
+
+ if (btrfs_is_testing(fs_info))
+ return;
+
+ btrfs_inode_rsv_release(inode, qgroup_free);
+}
+
+/**
+ * btrfs_delalloc_release_extents - release our outstanding_extents
+ * @inode: the inode to balance the reservation for.
+ * @num_bytes: the number of bytes we originally reserved with
+ *
+ * When we reserve space we increase outstanding_extents for the extents we may
+ * add. Once we've set the range as delalloc or created our ordered extents we
+ * have outstanding_extents to track the real usage, so we use this to free our
+ * temporarily tracked outstanding_extents. This _must_ be used in conjunction
+ * with btrfs_delalloc_reserve_metadata.
+ */
+void btrfs_delalloc_release_extents(struct btrfs_inode *inode, u64 num_bytes)
+{
+ struct btrfs_fs_info *fs_info = inode->root->fs_info;
+ unsigned num_extents;
+
+ spin_lock(&inode->lock);
+ num_extents = count_max_extents(fs_info, num_bytes);
+ btrfs_mod_outstanding_extents(inode, -num_extents);
+ btrfs_calculate_inode_block_rsv_size(fs_info, inode);
+ spin_unlock(&inode->lock);
+
+ if (btrfs_is_testing(fs_info))
+ return;
+
+ btrfs_inode_rsv_release(inode, true);
+}
+
+/**
+ * btrfs_delalloc_reserve_space - reserve data and metadata space for
+ * delalloc
+ * @inode: inode we're writing to
+ * @start: start range we are writing to
+ * @len: how long the range we are writing to
+ * @reserved: mandatory parameter, record actually reserved qgroup ranges of
+ * current reservation.
+ *
+ * This will do the following things
+ *
+ * - reserve space in data space info for num bytes
+ * and reserve precious corresponding qgroup space
+ * (Done in check_data_free_space)
+ *
+ * - reserve space for metadata space, based on the number of outstanding
+ * extents and how much csums will be needed
+ * also reserve metadata space in a per root over-reserve method.
+ * - add to the inodes->delalloc_bytes
+ * - add it to the fs_info's delalloc inodes list.
+ * (Above 3 all done in delalloc_reserve_metadata)
+ *
+ * Return 0 for success
+ * Return <0 for error(-ENOSPC or -EQUOT)
+ */
+int btrfs_delalloc_reserve_space(struct btrfs_inode *inode,
+ struct extent_changeset **reserved, u64 start, u64 len)
+{
+ int ret;
+
+ ret = btrfs_check_data_free_space(inode, reserved, start, len, false);
+ if (ret < 0)
+ return ret;
+ ret = btrfs_delalloc_reserve_metadata(inode, len, len, false);
+ if (ret < 0) {
+ btrfs_free_reserved_data_space(inode, *reserved, start, len);
+ extent_changeset_free(*reserved);
+ *reserved = NULL;
+ }
+ return ret;
+}
+
+/**
+ * Release data and metadata space for delalloc
+ *
+ * @inode: inode we're releasing space for
+ * @reserved: list of changed/reserved ranges
+ * @start: start position of the space already reserved
+ * @len: length of the space already reserved
+ * @qgroup_free: should qgroup reserved-space also be freed
+ *
+ * This function will release the metadata space that was not used and will
+ * decrement ->delalloc_bytes and remove it from the fs_info delalloc_inodes
+ * list if there are no delalloc bytes left.
+ * Also it will handle the qgroup reserved space.
+ */
+void btrfs_delalloc_release_space(struct btrfs_inode *inode,
+ struct extent_changeset *reserved,
+ u64 start, u64 len, bool qgroup_free)
+{
+ btrfs_delalloc_release_metadata(inode, len, qgroup_free);
+ btrfs_free_reserved_data_space(inode, reserved, start, len);
+}
generated by cgit v1.2.3 (git 2.39.1) at 2024-06-08 23:28:23 +0000