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btrfs: move btrfs_truncate_block out of trans handle 

Since we do a delalloc reserve in btrfs_truncate_block we can deadlock
with freeze.  If somebody else is trying to allocate metadata for this
inode and it gets stuck in start_delalloc_inodes because of freeze we
will deadlock.  Be safe and move this outside of a trans handle.  This
also has a side-effect of making sure that we're not leaving stale data
behind in the other_encoding or encryption case.  Not an issue now since
nobody uses it, but it would be a problem in the future.

Signed-off-by: Josef Bacik <jbacik@fb.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This commit is contained in:
Josef Bacik 2017-10-19 14:16:02 -04:00 committed by David Sterba
parent ce8ea7cc6e
commit ddfae63cc8
1 changed files with 45 additions and 75 deletions
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114
fs/btrfs/inode.c
View File

@ -4360,47 +4360,11 @@ static int truncate_space_check(struct btrfs_trans_handle *trans,
}
static int truncate_inline_extent(struct inode *inode,
struct btrfs_path *path,
struct btrfs_key *found_key,
const u64 item_end,
const u64 new_size)
{
struct extent_buffer *leaf = path->nodes[0];
int slot = path->slots[0];
struct btrfs_file_extent_item *fi;
u32 size = (u32)(new_size - found_key->offset);
struct btrfs_root *root = BTRFS_I(inode)->root;
fi = btrfs_item_ptr(leaf, slot, struct btrfs_file_extent_item);
if (btrfs_file_extent_compression(leaf, fi) != BTRFS_COMPRESS_NONE) {
loff_t offset = new_size;
loff_t page_end = ALIGN(offset, PAGE_SIZE);
/*
* Zero out the remaining of the last page of our inline extent,
* instead of directly truncating our inline extent here - that
* would be much more complex (decompressing all the data, then
* compressing the truncated data, which might be bigger than
* the size of the inline extent, resize the extent, etc).
* We release the path because to get the page we might need to
* read the extent item from disk (data not in the page cache).
/*
* Return this if we need to call truncate_block for the last bit of the
* truncate.
*/
btrfs_release_path(path);
return btrfs_truncate_block(inode, offset, page_end - offset,
0);
}
btrfs_set_file_extent_ram_bytes(leaf, fi, size);
size = btrfs_file_extent_calc_inline_size(size);
btrfs_truncate_item(root->fs_info, path, size, 1);
if (test_bit(BTRFS_ROOT_REF_COWS, &root->state))
inode_sub_bytes(inode, item_end + 1 - new_size);
return 0;
}
#define NEED_TRUNCATE_BLOCK 1
/*
* this can truncate away extent items, csum items and directory items.
@ -4561,11 +4525,6 @@ search_again:
if (found_type != BTRFS_EXTENT_DATA_KEY)
goto delete;
if (del_item)
last_size = found_key.offset;
else
last_size = new_size;
if (extent_type != BTRFS_FILE_EXTENT_INLINE) {
u64 num_dec;
extent_start = btrfs_file_extent_disk_bytenr(leaf, fi);
@ -4607,40 +4566,30 @@ search_again:
*/
if (!del_item &&
btrfs_file_extent_encryption(leaf, fi) == 0 &&
btrfs_file_extent_other_encoding(leaf, fi) == 0) {
btrfs_file_extent_other_encoding(leaf, fi) == 0 &&
btrfs_file_extent_compression(leaf, fi) == 0) {
u32 size = (u32)(new_size - found_key.offset);
btrfs_set_file_extent_ram_bytes(leaf, fi, size);
size = btrfs_file_extent_calc_inline_size(size);
btrfs_truncate_item(root->fs_info, path, size, 1);
} else if (!del_item) {
/*
* Need to release path in order to truncate a
* compressed extent. So delete any accumulated
* extent items so far.
* We have to bail so the last_size is set to
* just before this extent.
*/
if (btrfs_file_extent_compression(leaf, fi) !=
BTRFS_COMPRESS_NONE && pending_del_nr) {
err = btrfs_del_items(trans, root, path,
pending_del_slot,
pending_del_nr);
if (err) {
btrfs_abort_transaction(trans,
err);
goto error;
}
pending_del_nr = 0;
err = NEED_TRUNCATE_BLOCK;
break;
}
err = truncate_inline_extent(inode, path,
&found_key,
item_end,
new_size);
if (err) {
btrfs_abort_transaction(trans, err);
goto error;
}
} else if (test_bit(BTRFS_ROOT_REF_COWS,
&root->state)) {
if (test_bit(BTRFS_ROOT_REF_COWS, &root->state))
inode_sub_bytes(inode, item_end + 1 - new_size);
}
}
delete:
if (del_item)
last_size = found_key.offset;
else
last_size = new_size;
if (del_item) {
if (!pending_del_nr) {
/* no pending yet, add ourselves */
@ -9338,12 +9287,12 @@ static int btrfs_truncate(struct inode *inode)
ret = btrfs_truncate_inode_items(trans, root, inode,
inode->i_size,
BTRFS_EXTENT_DATA_KEY);
trans->block_rsv = &fs_info->trans_block_rsv;
if (ret != -ENOSPC && ret != -EAGAIN) {
err = ret;
break;
}
trans->block_rsv = &fs_info->trans_block_rsv;
ret = btrfs_update_inode(trans, root, inode);
if (ret) {
err = ret;
@ -9367,6 +9316,27 @@ static int btrfs_truncate(struct inode *inode)
trans->block_rsv = rsv;
}
/*
* We can't call btrfs_truncate_block inside a trans handle as we could
* deadlock with freeze, if we got NEED_TRUNCATE_BLOCK then we know
* we've truncated everything except the last little bit, and can do
* btrfs_truncate_block and then update the disk_i_size.
*/
if (ret == NEED_TRUNCATE_BLOCK) {
btrfs_end_transaction(trans);
btrfs_btree_balance_dirty(fs_info);
ret = btrfs_truncate_block(inode, inode->i_size, 0, 0);
if (ret)
goto out;
trans = btrfs_start_transaction(root, 1);
if (IS_ERR(trans)) {
ret = PTR_ERR(trans);
goto out;
}
btrfs_ordered_update_i_size(inode, inode->i_size, NULL);
}
if (ret == 0 && inode->i_nlink > 0) {
trans->block_rsv = root->orphan_block_rsv;
ret = btrfs_orphan_del(trans, BTRFS_I(inode));