From: Qu Wenruo Date: Mon, 26 Jul 2021 06:34:57 +0000 (+0800) Subject: btrfs: make relocate_one_page() handle subpage case X-Git-Tag: accepted/tizen/unified/20230118.172025~6109^2~93 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=c2832898126fc320a0e2915b07bf8924cf54770e;p=platform%2Fkernel%2Flinux-rpi.git 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 Signed-off-by: David Sterba --- diff --git a/fs/btrfs/relocation.c b/fs/btrfs/relocation.c index e28c3b93..9c8cea5 100644 --- a/fs/btrfs/relocation.c +++ b/fs/btrfs/relocation.c @@ -24,6 +24,7 @@ #include "block-group.h" #include "backref.h" #include "misc.h" +#include "subpage.h" /* * Relocation overview @@ -2886,6 +2887,17 @@ noinline int btrfs_should_cancel_balance(struct btrfs_fs_info *fs_info) } ALLOW_ERROR_INJECTION(btrfs_should_cancel_balance, TRUE); +static u64 get_cluster_boundary_end(struct file_extent_cluster *cluster, + int cluster_nr) +{ + /* Last extent, use cluster end directly */ + if (cluster_nr >= cluster->nr - 1) + return cluster->end; + + /* Use next boundary start*/ + return cluster->boundary[cluster_nr + 1] - 1; +} + static int relocate_one_page(struct inode *inode, struct file_ra_state *ra, struct file_extent_cluster *cluster, int *cluster_nr, unsigned long page_index) @@ -2897,22 +2909,17 @@ static int relocate_one_page(struct inode *inode, struct file_ra_state *ra, struct page *page; u64 page_start; u64 page_end; + u64 cur; int ret; ASSERT(page_index <= last_index); - ret = btrfs_delalloc_reserve_metadata(BTRFS_I(inode), PAGE_SIZE); - if (ret) - return ret; - page = find_lock_page(inode->i_mapping, page_index); if (!page) { page_cache_sync_readahead(inode->i_mapping, ra, NULL, page_index, last_index + 1 - page_index); page = find_or_create_page(inode->i_mapping, page_index, mask); - if (!page) { - ret = -ENOMEM; - goto release_delalloc; - } + if (!page) + return -ENOMEM; } ret = set_page_extent_mapped(page); if (ret < 0) @@ -2934,30 +2941,74 @@ static int relocate_one_page(struct inode *inode, struct file_ra_state *ra, page_start = page_offset(page); page_end = page_start + PAGE_SIZE - 1; - lock_extent(&BTRFS_I(inode)->io_tree, page_start, page_end); - - if (*cluster_nr < cluster->nr && - page_start + offset == cluster->boundary[*cluster_nr]) { - set_extent_bits(&BTRFS_I(inode)->io_tree, page_start, page_end, - EXTENT_BOUNDARY); - (*cluster_nr)++; - } + /* + * Start from the cluster, as for subpage case, the cluster can start + * inside the page. + */ + cur = max(page_start, cluster->boundary[*cluster_nr] - offset); + while (cur <= page_end) { + u64 extent_start = cluster->boundary[*cluster_nr] - offset; + u64 extent_end = get_cluster_boundary_end(cluster, + *cluster_nr) - offset; + u64 clamped_start = max(page_start, extent_start); + u64 clamped_end = min(page_end, extent_end); + u32 clamped_len = clamped_end + 1 - clamped_start; + + /* Reserve metadata for this range */ + ret = btrfs_delalloc_reserve_metadata(BTRFS_I(inode), + clamped_len); + if (ret) + goto release_page; - ret = btrfs_set_extent_delalloc(BTRFS_I(inode), page_start, page_end, - 0, NULL); - if (ret) { - clear_extent_bits(&BTRFS_I(inode)->io_tree, page_start, - page_end, EXTENT_LOCKED | EXTENT_BOUNDARY); - goto release_page; + /* Mark the range delalloc and dirty for later writeback */ + lock_extent(&BTRFS_I(inode)->io_tree, clamped_start, clamped_end); + ret = btrfs_set_extent_delalloc(BTRFS_I(inode), clamped_start, + clamped_end, 0, NULL); + if (ret) { + clear_extent_bits(&BTRFS_I(inode)->io_tree, + clamped_start, clamped_end, + EXTENT_LOCKED | EXTENT_BOUNDARY); + btrfs_delalloc_release_metadata(BTRFS_I(inode), + clamped_len, true); + btrfs_delalloc_release_extents(BTRFS_I(inode), + clamped_len); + goto release_page; + } + btrfs_page_set_dirty(fs_info, page, clamped_start, clamped_len); + /* + * Set the boundary if it's inside the page. + * Data relocation requires the destination extents to have the + * same size as the source. + * EXTENT_BOUNDARY bit prevents current extent from being merged + * with previous extent. + */ + if (in_range(cluster->boundary[*cluster_nr] - offset, + page_start, PAGE_SIZE)) { + u64 boundary_start = cluster->boundary[*cluster_nr] - + offset; + u64 boundary_end = boundary_start + + fs_info->sectorsize - 1; + + set_extent_bits(&BTRFS_I(inode)->io_tree, + boundary_start, boundary_end, + EXTENT_BOUNDARY); + } + unlock_extent(&BTRFS_I(inode)->io_tree, clamped_start, clamped_end); + btrfs_delalloc_release_extents(BTRFS_I(inode), clamped_len); + cur += clamped_len; + + /* Crossed extent end, go to next extent */ + if (cur >= extent_end) { + (*cluster_nr)++; + /* Just finished the last extent of the cluster, exit. */ + if (*cluster_nr >= cluster->nr) + break; + } } - set_page_dirty(page); - - unlock_extent(&BTRFS_I(inode)->io_tree, page_start, page_end); unlock_page(page); put_page(page); - btrfs_delalloc_release_extents(BTRFS_I(inode), PAGE_SIZE); balance_dirty_pages_ratelimited(inode->i_mapping); btrfs_throttle(fs_info); if (btrfs_should_cancel_balance(fs_info)) @@ -2967,9 +3018,6 @@ static int relocate_one_page(struct inode *inode, struct file_ra_state *ra, release_page: unlock_page(page); put_page(page); -release_delalloc: - btrfs_delalloc_release_metadata(BTRFS_I(inode), PAGE_SIZE, true); - btrfs_delalloc_release_extents(BTRFS_I(inode), PAGE_SIZE); return ret; }