From 97420be7bda57030110c7032ad190d320f2e0157 Mon Sep 17 00:00:00 2001 From: Filipe Manana Date: Tue, 24 Sep 2024 15:58:31 +0100 Subject: [PATCH] btrfs: use sector numbers as keys for the dirty extents xarray We are using the logical address ("bytenr") of an extent as the key for qgroup records in the dirty extents xarray. This is a problem because the xarrays use "unsigned long" for keys/indices, meaning that on a 32 bits platform any extent starting at or beyond 4G is truncated, which is a too low limitation as virtually everyone is using storage with more than 4G of space. This means a "bytenr" of 4G gets truncated to 0, and so does 8G and 16G for example, resulting in incorrect qgroup accounting. Fix this by using sector numbers as keys instead, that is, using keys that match the logical address right shifted by fs_info->sectorsize_bits, which is what we do for the fs_info->buffer_radix that tracks extent buffers (radix trees also use an "unsigned long" type for keys). This also makes the index space more dense which helps optimize the xarray (as mentioned at Documentation/core-api/xarray.rst). Fixes: 3cce39a8ca4e ("btrfs: qgroup: use xarray to track dirty extents in transaction") Reviewed-by: Qu Wenruo Signed-off-by: Filipe Manana Reviewed-by: David Sterba Signed-off-by: David Sterba --- fs/btrfs/delayed-ref.c | 15 ++++++++------- fs/btrfs/delayed-ref.h | 10 +++++++++- fs/btrfs/qgroup.c | 21 ++++++++++++++++----- 3 files changed, 33 insertions(+), 13 deletions(-) diff --git a/fs/btrfs/delayed-ref.c b/fs/btrfs/delayed-ref.c index 32f719b9e661..115b90d29b1d 100644 --- a/fs/btrfs/delayed-ref.c +++ b/fs/btrfs/delayed-ref.c @@ -849,6 +849,7 @@ add_delayed_ref_head(struct btrfs_trans_handle *trans, struct btrfs_qgroup_extent_record *qrecord, int action, bool *qrecord_inserted_ret) { + struct btrfs_fs_info *fs_info = trans->fs_info; struct btrfs_delayed_ref_head *existing; struct btrfs_delayed_ref_root *delayed_refs; bool qrecord_inserted = false; @@ -859,11 +860,11 @@ add_delayed_ref_head(struct btrfs_trans_handle *trans, if (qrecord) { int ret; - ret = btrfs_qgroup_trace_extent_nolock(trans->fs_info, - delayed_refs, qrecord); + ret = btrfs_qgroup_trace_extent_nolock(fs_info, delayed_refs, qrecord); if (ret) { /* Clean up if insertion fails or item exists. */ - xa_release(&delayed_refs->dirty_extents, qrecord->bytenr); + xa_release(&delayed_refs->dirty_extents, + qrecord->bytenr >> fs_info->sectorsize_bits); /* Caller responsible for freeing qrecord on error. */ if (ret < 0) return ERR_PTR(ret); @@ -873,7 +874,7 @@ add_delayed_ref_head(struct btrfs_trans_handle *trans, } } - trace_add_delayed_ref_head(trans->fs_info, head_ref, action); + trace_add_delayed_ref_head(fs_info, head_ref, action); existing = htree_insert(&delayed_refs->href_root, &head_ref->href_node); @@ -895,8 +896,7 @@ add_delayed_ref_head(struct btrfs_trans_handle *trans, if (head_ref->is_data && head_ref->ref_mod < 0) { delayed_refs->pending_csums += head_ref->num_bytes; trans->delayed_ref_csum_deletions += - btrfs_csum_bytes_to_leaves(trans->fs_info, - head_ref->num_bytes); + btrfs_csum_bytes_to_leaves(fs_info, head_ref->num_bytes); } delayed_refs->num_heads++; delayed_refs->num_heads_ready++; @@ -1030,7 +1030,8 @@ static int add_delayed_ref(struct btrfs_trans_handle *trans, goto free_head_ref; } if (xa_reserve(&trans->transaction->delayed_refs.dirty_extents, - generic_ref->bytenr, GFP_NOFS)) { + generic_ref->bytenr >> fs_info->sectorsize_bits, + GFP_NOFS)) { ret = -ENOMEM; goto free_record; } diff --git a/fs/btrfs/delayed-ref.h b/fs/btrfs/delayed-ref.h index 085f30968aba..352921e76c74 100644 --- a/fs/btrfs/delayed-ref.h +++ b/fs/btrfs/delayed-ref.h @@ -202,7 +202,15 @@ struct btrfs_delayed_ref_root { /* head ref rbtree */ struct rb_root_cached href_root; - /* Track dirty extent records. */ + /* + * Track dirty extent records. + * The keys correspond to the logical address of the extent ("bytenr") + * right shifted by fs_info->sectorsize_bits. This is both to get a more + * dense index space (optimizes xarray structure) and because indexes in + * xarrays are of "unsigned long" type, meaning they are 32 bits wide on + * 32 bits platforms, limiting the extent range to 4G which is too low + * and makes it unusable (truncated index values) on 32 bits platforms. + */ struct xarray dirty_extents; /* this spin lock protects the rbtree and the entries inside */ diff --git a/fs/btrfs/qgroup.c b/fs/btrfs/qgroup.c index c297909f1506..1332ec59c539 100644 --- a/fs/btrfs/qgroup.c +++ b/fs/btrfs/qgroup.c @@ -2005,16 +2005,26 @@ int btrfs_qgroup_trace_extent_nolock(struct btrfs_fs_info *fs_info, struct btrfs_qgroup_extent_record *record) { struct btrfs_qgroup_extent_record *existing, *ret; - unsigned long bytenr = record->bytenr; + const unsigned long index = (record->bytenr >> fs_info->sectorsize_bits); if (!btrfs_qgroup_full_accounting(fs_info)) return 1; +#if BITS_PER_LONG == 32 + if (record->bytenr >= MAX_LFS_FILESIZE) { + btrfs_err_rl(fs_info, +"qgroup record for extent at %llu is beyond 32bit page cache and xarray index limit", + record->bytenr); + btrfs_err_32bit_limit(fs_info); + return -EOVERFLOW; + } +#endif + lockdep_assert_held(&delayed_refs->lock); trace_btrfs_qgroup_trace_extent(fs_info, record); xa_lock(&delayed_refs->dirty_extents); - existing = xa_load(&delayed_refs->dirty_extents, bytenr); + existing = xa_load(&delayed_refs->dirty_extents, index); if (existing) { if (record->data_rsv && !existing->data_rsv) { existing->data_rsv = record->data_rsv; @@ -2024,7 +2034,7 @@ int btrfs_qgroup_trace_extent_nolock(struct btrfs_fs_info *fs_info, return 1; } - ret = __xa_store(&delayed_refs->dirty_extents, record->bytenr, record, GFP_ATOMIC); + ret = __xa_store(&delayed_refs->dirty_extents, index, record, GFP_ATOMIC); xa_unlock(&delayed_refs->dirty_extents); if (xa_is_err(ret)) { qgroup_mark_inconsistent(fs_info); @@ -2129,6 +2139,7 @@ int btrfs_qgroup_trace_extent(struct btrfs_trans_handle *trans, u64 bytenr, struct btrfs_fs_info *fs_info = trans->fs_info; struct btrfs_qgroup_extent_record *record; struct btrfs_delayed_ref_root *delayed_refs; + const unsigned long index = (bytenr >> fs_info->sectorsize_bits); int ret; if (!btrfs_qgroup_full_accounting(fs_info) || bytenr == 0 || num_bytes == 0) @@ -2137,7 +2148,7 @@ int btrfs_qgroup_trace_extent(struct btrfs_trans_handle *trans, u64 bytenr, if (!record) return -ENOMEM; - if (xa_reserve(&trans->transaction->delayed_refs.dirty_extents, bytenr, GFP_NOFS)) { + if (xa_reserve(&trans->transaction->delayed_refs.dirty_extents, index, GFP_NOFS)) { kfree(record); return -ENOMEM; } @@ -2152,7 +2163,7 @@ int btrfs_qgroup_trace_extent(struct btrfs_trans_handle *trans, u64 bytenr, spin_unlock(&delayed_refs->lock); if (ret) { /* Clean up if insertion fails or item exists. */ - xa_release(&delayed_refs->dirty_extents, record->bytenr); + xa_release(&delayed_refs->dirty_extents, index); kfree(record); return 0; }