From: Qu Wenruo wqu@suse.com
commit 263da812e87bac4098a4778efaa32c54275641db upstream
[PROBLEM] Before this patch, when btrfs_qgroup_reserve_data() fails, we free all reserved space of the changeset.
For example: ret = btrfs_qgroup_reserve_data(inode, changeset, 0, SZ_1M); ret = btrfs_qgroup_reserve_data(inode, changeset, SZ_1M, SZ_1M); ret = btrfs_qgroup_reserve_data(inode, changeset, SZ_2M, SZ_1M);
If the last btrfs_qgroup_reserve_data() failed, it will release the entire [0, 3M) range.
This behavior is kind of OK for now, as when we hit -EDQUOT, we normally go error handling and need to release all reserved ranges anyway.
But this also means the following call is not possible:
ret = btrfs_qgroup_reserve_data(); if (ret == -EDQUOT) { /* Do something to free some qgroup space */ ret = btrfs_qgroup_reserve_data(); }
As if the first btrfs_qgroup_reserve_data() fails, it will free all reserved qgroup space.
[CAUSE] This is because we release all reserved ranges when btrfs_qgroup_reserve_data() fails.
[FIX] This patch will implement a new function, qgroup_unreserve_range(), to iterate through the ulist nodes, to find any nodes in the failure range, and remove the EXTENT_QGROUP_RESERVED bits from the io_tree, and decrease the extent_changeset::bytes_changed, so that we can revert to previous state.
This allows later patches to retry btrfs_qgroup_reserve_data() if EDQUOT happens.
Suggested-by: Josef Bacik josef@toxicpanda.com Reviewed-by: Josef Bacik josef@toxicpanda.com Signed-off-by: Qu Wenruo wqu@suse.com Reviewed-by: David Sterba dsterba@suse.com Signed-off-by: David Sterba dsterba@suse.com Signed-off-by: Anand Jain anand.jain@oracle.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- fs/btrfs/qgroup.c | 92 +++++++++++++++++++++++++++++++++++++++++++++--------- 1 file changed, 77 insertions(+), 15 deletions(-)
--- a/fs/btrfs/qgroup.c +++ b/fs/btrfs/qgroup.c @@ -3411,6 +3411,73 @@ btrfs_qgroup_rescan_resume(struct btrfs_ } }
+#define rbtree_iterate_from_safe(node, next, start) \ + for (node = start; node && ({ next = rb_next(node); 1;}); node = next) + +static int qgroup_unreserve_range(struct btrfs_inode *inode, + struct extent_changeset *reserved, u64 start, + u64 len) +{ + struct rb_node *node; + struct rb_node *next; + struct ulist_node *entry = NULL; + int ret = 0; + + node = reserved->range_changed.root.rb_node; + while (node) { + entry = rb_entry(node, struct ulist_node, rb_node); + if (entry->val < start) + node = node->rb_right; + else if (entry) + node = node->rb_left; + else + break; + } + + /* Empty changeset */ + if (!entry) + return 0; + + if (entry->val > start && rb_prev(&entry->rb_node)) + entry = rb_entry(rb_prev(&entry->rb_node), struct ulist_node, + rb_node); + + rbtree_iterate_from_safe(node, next, &entry->rb_node) { + u64 entry_start; + u64 entry_end; + u64 entry_len; + int clear_ret; + + entry = rb_entry(node, struct ulist_node, rb_node); + entry_start = entry->val; + entry_end = entry->aux; + entry_len = entry_end - entry_start + 1; + + if (entry_start >= start + len) + break; + if (entry_start + entry_len <= start) + continue; + /* + * Now the entry is in [start, start + len), revert the + * EXTENT_QGROUP_RESERVED bit. + */ + clear_ret = clear_extent_bits(&inode->io_tree, entry_start, + entry_end, EXTENT_QGROUP_RESERVED); + if (!ret && clear_ret < 0) + ret = clear_ret; + + ulist_del(&reserved->range_changed, entry->val, entry->aux); + if (likely(reserved->bytes_changed >= entry_len)) { + reserved->bytes_changed -= entry_len; + } else { + WARN_ON(1); + reserved->bytes_changed = 0; + } + } + + return ret; +} + /* * Reserve qgroup space for range [start, start + len). * @@ -3421,18 +3488,14 @@ btrfs_qgroup_rescan_resume(struct btrfs_ * Return <0 for error (including -EQUOT) * * NOTE: this function may sleep for memory allocation. - * if btrfs_qgroup_reserve_data() is called multiple times with - * same @reserved, caller must ensure when error happens it's OK - * to free *ALL* reserved space. */ int btrfs_qgroup_reserve_data(struct btrfs_inode *inode, struct extent_changeset **reserved_ret, u64 start, u64 len) { struct btrfs_root *root = inode->root; - struct ulist_node *unode; - struct ulist_iterator uiter; struct extent_changeset *reserved; + bool new_reserved = false; u64 orig_reserved; u64 to_reserve; int ret; @@ -3445,6 +3508,7 @@ int btrfs_qgroup_reserve_data(struct btr if (WARN_ON(!reserved_ret)) return -EINVAL; if (!*reserved_ret) { + new_reserved = true; *reserved_ret = extent_changeset_alloc(); if (!*reserved_ret) return -ENOMEM; @@ -3460,7 +3524,7 @@ int btrfs_qgroup_reserve_data(struct btr trace_btrfs_qgroup_reserve_data(&inode->vfs_inode, start, len, to_reserve, QGROUP_RESERVE); if (ret < 0) - goto cleanup; + goto out; ret = qgroup_reserve(root, to_reserve, true, BTRFS_QGROUP_RSV_DATA); if (ret < 0) goto cleanup; @@ -3468,15 +3532,13 @@ int btrfs_qgroup_reserve_data(struct btr return ret;
cleanup: - /* cleanup *ALL* already reserved ranges */ - ULIST_ITER_INIT(&uiter); - while ((unode = ulist_next(&reserved->range_changed, &uiter))) - clear_extent_bit(&inode->io_tree, unode->val, - unode->aux, EXTENT_QGROUP_RESERVED, 0, 0, NULL); - /* Also free data bytes of already reserved one */ - btrfs_qgroup_free_refroot(root->fs_info, root->root_key.objectid, - orig_reserved, BTRFS_QGROUP_RSV_DATA); - extent_changeset_release(reserved); + qgroup_unreserve_range(inode, reserved, start, len); +out: + if (new_reserved) { + extent_changeset_release(reserved); + kfree(reserved); + *reserved_ret = NULL; + } return ret; }