On Mon, Jun 01, 2015 at 08:52:52PM +0530, Chandan Rajendra wrote:
> In subpagesize-blocksize a page can map multiple extent buffers and hence
> using (page index, seq) as the search key is incorrect. For example, searching
> through tree modification log tree can return an entry associated with the
> first extent buffer mapped by the page (if such an entry exists), when we are
> actually searching for entries associated with extent buffers that are mapped
> at position 2 or more in the page.
Reviewed-by: Liu Bo <bo.li....@oracle.com>
Thanks,
-liubo
>
> Signed-off-by: Chandan Rajendra <chan...@linux.vnet.ibm.com>
> ---
> fs/btrfs/ctree.c | 34 +++++++++++++++++-----------------
> 1 file changed, 17 insertions(+), 17 deletions(-)
>
> diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c
> index ba6fbb0..47310d3 100644
> --- a/fs/btrfs/ctree.c
> +++ b/fs/btrfs/ctree.c
> @@ -311,7 +311,7 @@ struct tree_mod_root {
>
> struct tree_mod_elem {
> struct rb_node node;
> - u64 index; /* shifted logical */
> + u64 logical;
> u64 seq;
> enum mod_log_op op;
>
> @@ -435,11 +435,11 @@ void btrfs_put_tree_mod_seq(struct btrfs_fs_info
> *fs_info,
>
> /*
> * key order of the log:
> - * index -> sequence
> + * node/leaf start address -> sequence
> *
> - * the index is the shifted logical of the *new* root node for root replace
> - * operations, or the shifted logical of the affected block for all other
> - * operations.
> + * The 'start address' is the logical address of the *new* root node
> + * for root replace operations, or the logical address of the affected
> + * block for all other operations.
> *
> * Note: must be called with write lock (tree_mod_log_write_lock).
> */
> @@ -460,9 +460,9 @@ __tree_mod_log_insert(struct btrfs_fs_info *fs_info,
> struct tree_mod_elem *tm)
> while (*new) {
> cur = container_of(*new, struct tree_mod_elem, node);
> parent = *new;
> - if (cur->index < tm->index)
> + if (cur->logical < tm->logical)
> new = &((*new)->rb_left);
> - else if (cur->index > tm->index)
> + else if (cur->logical > tm->logical)
> new = &((*new)->rb_right);
> else if (cur->seq < tm->seq)
> new = &((*new)->rb_left);
> @@ -523,7 +523,7 @@ alloc_tree_mod_elem(struct extent_buffer *eb, int slot,
> if (!tm)
> return NULL;
>
> - tm->index = eb->start >> PAGE_CACHE_SHIFT;
> + tm->logical = eb->start;
> if (op != MOD_LOG_KEY_ADD) {
> btrfs_node_key(eb, &tm->key, slot);
> tm->blockptr = btrfs_node_blockptr(eb, slot);
> @@ -588,7 +588,7 @@ tree_mod_log_insert_move(struct btrfs_fs_info *fs_info,
> goto free_tms;
> }
>
> - tm->index = eb->start >> PAGE_CACHE_SHIFT;
> + tm->logical = eb->start;
> tm->slot = src_slot;
> tm->move.dst_slot = dst_slot;
> tm->move.nr_items = nr_items;
> @@ -699,7 +699,7 @@ tree_mod_log_insert_root(struct btrfs_fs_info *fs_info,
> goto free_tms;
> }
>
> - tm->index = new_root->start >> PAGE_CACHE_SHIFT;
> + tm->logical = new_root->start;
> tm->old_root.logical = old_root->start;
> tm->old_root.level = btrfs_header_level(old_root);
> tm->generation = btrfs_header_generation(old_root);
> @@ -739,16 +739,15 @@ __tree_mod_log_search(struct btrfs_fs_info *fs_info,
> u64 start, u64 min_seq,
> struct rb_node *node;
> struct tree_mod_elem *cur = NULL;
> struct tree_mod_elem *found = NULL;
> - u64 index = start >> PAGE_CACHE_SHIFT;
>
> tree_mod_log_read_lock(fs_info);
> tm_root = &fs_info->tree_mod_log;
> node = tm_root->rb_node;
> while (node) {
> cur = container_of(node, struct tree_mod_elem, node);
> - if (cur->index < index) {
> + if (cur->logical < start) {
> node = node->rb_left;
> - } else if (cur->index > index) {
> + } else if (cur->logical > start) {
> node = node->rb_right;
> } else if (cur->seq < min_seq) {
> node = node->rb_left;
> @@ -1228,9 +1227,10 @@ __tree_mod_log_oldest_root(struct btrfs_fs_info
> *fs_info,
> return NULL;
>
> /*
> - * the very last operation that's logged for a root is the replacement
> - * operation (if it is replaced at all). this has the index of the *new*
> - * root, making it the very first operation that's logged for this root.
> + * the very last operation that's logged for a root is the
> + * replacement operation (if it is replaced at all). this has
> + * the logical address of the *new* root, making it the very
> + * first operation that's logged for this root.
> */
> while (1) {
> tm = tree_mod_log_search_oldest(fs_info, root_logical,
> @@ -1334,7 +1334,7 @@ __tree_mod_log_rewind(struct btrfs_fs_info *fs_info,
> struct extent_buffer *eb,
> if (!next)
> break;
> tm = container_of(next, struct tree_mod_elem, node);
> - if (tm->index != first_tm->index)
> + if (tm->logical != first_tm->logical)
> break;
> }
> tree_mod_log_read_unlock(fs_info);
> --
> 2.1.0
>
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