From d0b7da88f6409c740435712b092a8e2c7d2a8f74 Mon Sep 17 00:00:00 2001 From: Chandan Rajendra Date: Thu, 21 Jan 2016 15:55:57 +0530 Subject: [PATCH] Btrfs: btrfs_page_mkwrite: Reserve space in sectorsized units In subpagesize-blocksize scenario, if i_size occurs in a block which is not the last block in the page, then the space to be reserved should be calculated appropriately. Reviewed-by: Liu Bo Signed-off-by: Chandan Rajendra Signed-off-by: David Sterba --- fs/btrfs/inode.c | 35 ++++++++++++++++++++++++++++++----- 1 file changed, 30 insertions(+), 5 deletions(-) diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c index 0bfd7fb2e83c..ad27f5d1a4a1 100644 --- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -8802,15 +8802,28 @@ int btrfs_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf) loff_t size; int ret; int reserved = 0; + u64 reserved_space; u64 page_start; u64 page_end; + u64 end; + + reserved_space = PAGE_CACHE_SIZE; sb_start_pagefault(inode->i_sb); page_start = page_offset(page); page_end = page_start + PAGE_CACHE_SIZE - 1; + end = page_end; + /* + * Reserving delalloc space after obtaining the page lock can lead to + * deadlock. For example, if a dirty page is locked by this function + * and the call to btrfs_delalloc_reserve_space() ends up triggering + * dirty page write out, then the btrfs_writepage() function could + * end up waiting indefinitely to get a lock on the page currently + * being processed by btrfs_page_mkwrite() function. + */ ret = btrfs_delalloc_reserve_space(inode, page_start, - PAGE_CACHE_SIZE); + reserved_space); if (!ret) { ret = file_update_time(vma->vm_file); reserved = 1; @@ -8844,7 +8857,7 @@ again: * we can't set the delalloc bits if there are pending ordered * extents. Drop our locks and wait for them to finish */ - ordered = btrfs_lookup_ordered_extent(inode, page_start); + ordered = btrfs_lookup_ordered_range(inode, page_start, page_end); if (ordered) { unlock_extent_cached(io_tree, page_start, page_end, &cached_state, GFP_NOFS); @@ -8854,6 +8867,18 @@ again: goto again; } + if (page->index == ((size - 1) >> PAGE_CACHE_SHIFT)) { + reserved_space = round_up(size - page_start, root->sectorsize); + if (reserved_space < PAGE_CACHE_SIZE) { + end = page_start + reserved_space - 1; + spin_lock(&BTRFS_I(inode)->lock); + BTRFS_I(inode)->outstanding_extents++; + spin_unlock(&BTRFS_I(inode)->lock); + btrfs_delalloc_release_space(inode, page_start, + PAGE_CACHE_SIZE - reserved_space); + } + } + /* * XXX - page_mkwrite gets called every time the page is dirtied, even * if it was already dirty, so for space accounting reasons we need to @@ -8861,12 +8886,12 @@ again: * is probably a better way to do this, but for now keep consistent with * prepare_pages in the normal write path. */ - clear_extent_bit(&BTRFS_I(inode)->io_tree, page_start, page_end, + clear_extent_bit(&BTRFS_I(inode)->io_tree, page_start, end, EXTENT_DIRTY | EXTENT_DELALLOC | EXTENT_DO_ACCOUNTING | EXTENT_DEFRAG, 0, 0, &cached_state, GFP_NOFS); - ret = btrfs_set_extent_delalloc(inode, page_start, page_end, + ret = btrfs_set_extent_delalloc(inode, page_start, end, &cached_state); if (ret) { unlock_extent_cached(io_tree, page_start, page_end, @@ -8905,7 +8930,7 @@ out_unlock: } unlock_page(page); out: - btrfs_delalloc_release_space(inode, page_start, PAGE_CACHE_SIZE); + btrfs_delalloc_release_space(inode, page_start, reserved_space); out_noreserve: sb_end_pagefault(inode->i_sb); return ret; -- 2.20.1