From 69ffb54347a71c4f2a4694e0c1155af8538d55f6 Mon Sep 17 00:00:00 2001 From: Josef Bacik Date: Tue, 11 Sep 2012 15:40:07 -0400 Subject: [PATCH] Btrfs: create a pinned em when writing to a prealloc range in DIO Wade Cline reported a problem where he was getting garbage and warnings when writing to a preallocated range via O_DIRECT. This is because we weren't creating our normal pinned extent_map for the range we were writing to, which was causing all sorts of issues. This patch fixes the problem and makes his testcase much happier. Thanks, Reported-by: Wade Cline Signed-off-by: Josef Bacik --- fs/btrfs/inode.c | 55 ++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 55 insertions(+) diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c index 9e9754adf7a4..406666cb6156 100644 --- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -5898,6 +5898,48 @@ static int lock_extent_direct(struct inode *inode, u64 lockstart, u64 lockend, return ret; } +static struct extent_map *create_pinned_em(struct inode *inode, u64 start, + u64 len, u64 orig_start, + u64 block_start, u64 block_len, + int type) +{ + struct extent_map_tree *em_tree; + struct extent_map *em; + struct btrfs_root *root = BTRFS_I(inode)->root; + int ret; + + em_tree = &BTRFS_I(inode)->extent_tree; + em = alloc_extent_map(); + if (!em) + return ERR_PTR(-ENOMEM); + + em->start = start; + em->orig_start = orig_start; + em->len = len; + em->block_len = block_len; + em->block_start = block_start; + em->bdev = root->fs_info->fs_devices->latest_bdev; + set_bit(EXTENT_FLAG_PINNED, &em->flags); + if (type == BTRFS_ORDERED_PREALLOC) + set_bit(EXTENT_FLAG_PREALLOC, &em->flags); + + do { + btrfs_drop_extent_cache(inode, em->start, + em->start + em->len - 1, 0); + write_lock(&em_tree->lock); + ret = add_extent_mapping(em_tree, em); + write_unlock(&em_tree->lock); + } while (ret == -EEXIST); + + if (ret) { + free_extent_map(em); + return ERR_PTR(ret); + } + + return em; +} + + static int btrfs_get_blocks_direct(struct inode *inode, sector_t iblock, struct buffer_head *bh_result, int create) { @@ -6012,6 +6054,19 @@ static int btrfs_get_blocks_direct(struct inode *inode, sector_t iblock, goto must_cow; if (can_nocow_odirect(trans, inode, start, len) == 1) { + u64 orig_start = em->start; + + if (type == BTRFS_ORDERED_PREALLOC) { + free_extent_map(em); + em = create_pinned_em(inode, start, len, + orig_start, + block_start, len, type); + if (IS_ERR(em)) { + btrfs_end_transaction(trans, root); + goto unlock_err; + } + } + ret = btrfs_add_ordered_extent_dio(inode, start, block_start, len, len, type); btrfs_end_transaction(trans, root); -- 2.20.1