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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 <clinew@linux.vnet.ibm.com>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
wifi-calibration
Josef Bacik 2012-09-11 15:40:07 -04:00 committed by Chris Mason
parent 6df7881a84
commit 69ffb54347
1 changed files with 55 additions and 0 deletions
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55
fs/btrfs/inode.c
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@ -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);