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btrfs: make relocate_one_page() handle subpage case
For subpage case, one page of data reloc inode can contain several file extents, like this: |<--- File extent A --->| FE B | FE C |<--- File extent D -->| |<--------- Page --------->| We can no longer use PAGE_SIZE directly for various operations. This patch will relocate_one_page() to handle subpage case by: - Iterating through all extents of a cluster when marking pages When marking pages dirty and delalloc, we need to check the cluster extent boundary. Now we introduce a loop to go extent by extent of a page, until we either finished the last extent, or reach the page end. By this, regular sectorsize == PAGE_SIZE can still work as usual, since we will do that loop only once. - Iteration start from max(page_start, extent_start) Since we can have the following case: | FE B | FE C |<--- File extent D -->| |<--------- Page --------->| Thus we can't always start from page_start, but do a max(page_start, extent_start) - Iteration end when the cluster is exhausted Similar to previous case, the last file extent can end before the page end: |<--- File extent A --->| FE B | FE C | |<--------- Page --------->| In this case, we need to manually exit the loop after we have finished the last extent of the cluster. - Reserve metadata space for each extent range Since now we can hit multiple ranges in one page, we should reserve metadata for each range, not simply PAGE_SIZE. Signed-off-by: Qu Wenruo <wqu@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
This commit is contained in:
Qu Wenruo
David Sterba
parent
f47960f49e
commit
c283289812
@ -24,6 +24,7 @@
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#include "block-group.h"
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#include "backref.h"
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#include "misc.h"
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#include "subpage.h"
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/*
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* Relocation overview
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@ -2886,6 +2887,17 @@ noinline int btrfs_should_cancel_balance(struct btrfs_fs_info *fs_info)
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}
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ALLOW_ERROR_INJECTION(btrfs_should_cancel_balance, TRUE);
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static u64 get_cluster_boundary_end(struct file_extent_cluster *cluster,
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int cluster_nr)
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{
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/* Last extent, use cluster end directly */
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if (cluster_nr >= cluster->nr - 1)
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return cluster->end;
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/* Use next boundary start*/
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return cluster->boundary[cluster_nr + 1] - 1;
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}
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static int relocate_one_page(struct inode *inode, struct file_ra_state *ra,
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struct file_extent_cluster *cluster,
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int *cluster_nr, unsigned long page_index)
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@ -2897,22 +2909,17 @@ static int relocate_one_page(struct inode *inode, struct file_ra_state *ra,
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struct page *page;
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u64 page_start;
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u64 page_end;
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u64 cur;
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int ret;
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ASSERT(page_index <= last_index);
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ret = btrfs_delalloc_reserve_metadata(BTRFS_I(inode), PAGE_SIZE);
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if (ret)
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return ret;
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page = find_lock_page(inode->i_mapping, page_index);
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if (!page) {
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page_cache_sync_readahead(inode->i_mapping, ra, NULL,
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page_index, last_index + 1 - page_index);
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page = find_or_create_page(inode->i_mapping, page_index, mask);
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if (!page) {
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ret = -ENOMEM;
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goto release_delalloc;
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}
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if (!page)
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return -ENOMEM;
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}
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ret = set_page_extent_mapped(page);
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if (ret < 0)
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@ -2934,30 +2941,74 @@ static int relocate_one_page(struct inode *inode, struct file_ra_state *ra,
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page_start = page_offset(page);
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page_end = page_start + PAGE_SIZE - 1;
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lock_extent(&BTRFS_I(inode)->io_tree, page_start, page_end);
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/*
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* Start from the cluster, as for subpage case, the cluster can start
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* inside the page.
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*/
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cur = max(page_start, cluster->boundary[*cluster_nr] - offset);
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while (cur <= page_end) {
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u64 extent_start = cluster->boundary[*cluster_nr] - offset;
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u64 extent_end = get_cluster_boundary_end(cluster,
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*cluster_nr) - offset;
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u64 clamped_start = max(page_start, extent_start);
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u64 clamped_end = min(page_end, extent_end);
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u32 clamped_len = clamped_end + 1 - clamped_start;
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if (*cluster_nr < cluster->nr &&
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page_start + offset == cluster->boundary[*cluster_nr]) {
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set_extent_bits(&BTRFS_I(inode)->io_tree, page_start, page_end,
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EXTENT_BOUNDARY);
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(*cluster_nr)++;
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/* Reserve metadata for this range */
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ret = btrfs_delalloc_reserve_metadata(BTRFS_I(inode),
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clamped_len);
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if (ret)
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goto release_page;
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/* Mark the range delalloc and dirty for later writeback */
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lock_extent(&BTRFS_I(inode)->io_tree, clamped_start, clamped_end);
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ret = btrfs_set_extent_delalloc(BTRFS_I(inode), clamped_start,
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clamped_end, 0, NULL);
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if (ret) {
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clear_extent_bits(&BTRFS_I(inode)->io_tree,
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clamped_start, clamped_end,
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EXTENT_LOCKED | EXTENT_BOUNDARY);
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btrfs_delalloc_release_metadata(BTRFS_I(inode),
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clamped_len, true);
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btrfs_delalloc_release_extents(BTRFS_I(inode),
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clamped_len);
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goto release_page;
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}
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btrfs_page_set_dirty(fs_info, page, clamped_start, clamped_len);
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/*
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* Set the boundary if it's inside the page.
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* Data relocation requires the destination extents to have the
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* same size as the source.
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* EXTENT_BOUNDARY bit prevents current extent from being merged
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* with previous extent.
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*/
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if (in_range(cluster->boundary[*cluster_nr] - offset,
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page_start, PAGE_SIZE)) {
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u64 boundary_start = cluster->boundary[*cluster_nr] -
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offset;
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u64 boundary_end = boundary_start +
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fs_info->sectorsize - 1;
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set_extent_bits(&BTRFS_I(inode)->io_tree,
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boundary_start, boundary_end,
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EXTENT_BOUNDARY);
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}
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unlock_extent(&BTRFS_I(inode)->io_tree, clamped_start, clamped_end);
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btrfs_delalloc_release_extents(BTRFS_I(inode), clamped_len);
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cur += clamped_len;
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/* Crossed extent end, go to next extent */
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if (cur >= extent_end) {
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(*cluster_nr)++;
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/* Just finished the last extent of the cluster, exit. */
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if (*cluster_nr >= cluster->nr)
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break;
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}
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}
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ret = btrfs_set_extent_delalloc(BTRFS_I(inode), page_start, page_end,
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0, NULL);
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if (ret) {
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clear_extent_bits(&BTRFS_I(inode)->io_tree, page_start,
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page_end, EXTENT_LOCKED | EXTENT_BOUNDARY);
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goto release_page;
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}
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set_page_dirty(page);
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unlock_extent(&BTRFS_I(inode)->io_tree, page_start, page_end);
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unlock_page(page);
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put_page(page);
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btrfs_delalloc_release_extents(BTRFS_I(inode), PAGE_SIZE);
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balance_dirty_pages_ratelimited(inode->i_mapping);
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btrfs_throttle(fs_info);
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if (btrfs_should_cancel_balance(fs_info))
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@ -2967,9 +3018,6 @@ static int relocate_one_page(struct inode *inode, struct file_ra_state *ra,
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release_page:
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unlock_page(page);
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put_page(page);
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release_delalloc:
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btrfs_delalloc_release_metadata(BTRFS_I(inode), PAGE_SIZE, true);
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btrfs_delalloc_release_extents(BTRFS_I(inode), PAGE_SIZE);
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return ret;
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}
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