ext4: teach ext4_ext_map_blocks() about the bigalloc feature
If we need to allocate a new block in ext4_ext_map_blocks(), the function needs to see if the cluster has already been allocated. Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
This commit is contained in:
Theodore Ts'o
parent
84130193e0
commit
4d33b1ef10
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@ -1270,7 +1270,8 @@ static int ext4_ext_search_left(struct inode *inode,
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*/
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static int ext4_ext_search_right(struct inode *inode,
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struct ext4_ext_path *path,
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ext4_lblk_t *logical, ext4_fsblk_t *phys)
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ext4_lblk_t *logical, ext4_fsblk_t *phys,
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struct ext4_extent **ret_ex)
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{
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struct buffer_head *bh = NULL;
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struct ext4_extent_header *eh;
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@ -1312,9 +1313,7 @@ static int ext4_ext_search_right(struct inode *inode,
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return -EIO;
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}
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}
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*logical = le32_to_cpu(ex->ee_block);
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*phys = ext4_ext_pblock(ex);
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return 0;
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goto found_extent;
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}
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if (unlikely(*logical < (le32_to_cpu(ex->ee_block) + ee_len))) {
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@ -1327,9 +1326,7 @@ static int ext4_ext_search_right(struct inode *inode,
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if (ex != EXT_LAST_EXTENT(path[depth].p_hdr)) {
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/* next allocated block in this leaf */
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ex++;
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*logical = le32_to_cpu(ex->ee_block);
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*phys = ext4_ext_pblock(ex);
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return 0;
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goto found_extent;
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}
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/* go up and search for index to the right */
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@ -1372,9 +1369,12 @@ got_index:
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return -EIO;
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}
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ex = EXT_FIRST_EXTENT(eh);
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found_extent:
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*logical = le32_to_cpu(ex->ee_block);
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*phys = ext4_ext_pblock(ex);
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put_bh(bh);
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*ret_ex = ex;
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if (bh)
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put_bh(bh);
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return 0;
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}
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@ -1627,7 +1627,8 @@ static int ext4_ext_try_to_merge(struct inode *inode,
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* such that there will be no overlap, and then returns 1.
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* If there is no overlap found, it returns 0.
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*/
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static unsigned int ext4_ext_check_overlap(struct inode *inode,
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static unsigned int ext4_ext_check_overlap(struct ext4_sb_info *sbi,
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struct inode *inode,
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struct ext4_extent *newext,
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struct ext4_ext_path *path)
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{
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@ -1641,6 +1642,7 @@ static unsigned int ext4_ext_check_overlap(struct inode *inode,
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if (!path[depth].p_ext)
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goto out;
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b2 = le32_to_cpu(path[depth].p_ext->ee_block);
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b2 &= ~(sbi->s_cluster_ratio - 1);
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/*
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* get the next allocated block if the extent in the path
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@ -1650,6 +1652,7 @@ static unsigned int ext4_ext_check_overlap(struct inode *inode,
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b2 = ext4_ext_next_allocated_block(path);
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if (b2 == EXT_MAX_BLOCKS)
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goto out;
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b2 &= ~(sbi->s_cluster_ratio - 1);
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}
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/* check for wrap through zero on extent logical start block*/
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@ -3293,6 +3296,106 @@ out2:
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return err ? err : allocated;
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}
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/*
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* get_implied_cluster_alloc - check to see if the requested
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* allocation (in the map structure) overlaps with a cluster already
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* allocated in an extent.
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* @sbi The ext4-specific superblock structure
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* @map The requested lblk->pblk mapping
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* @ex The extent structure which might contain an implied
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* cluster allocation
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*
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* This function is called by ext4_ext_map_blocks() after we failed to
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* find blocks that were already in the inode's extent tree. Hence,
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* we know that the beginning of the requested region cannot overlap
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* the extent from the inode's extent tree. There are three cases we
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* want to catch. The first is this case:
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*
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* |--- cluster # N--|
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* |--- extent ---| |---- requested region ---|
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* |==========|
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*
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* The second case that we need to test for is this one:
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*
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* |--------- cluster # N ----------------|
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* |--- requested region --| |------- extent ----|
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* |=======================|
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*
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* The third case is when the requested region lies between two extents
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* within the same cluster:
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* |------------- cluster # N-------------|
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* |----- ex -----| |---- ex_right ----|
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* |------ requested region ------|
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* |================|
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*
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* In each of the above cases, we need to set the map->m_pblk and
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* map->m_len so it corresponds to the return the extent labelled as
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* "|====|" from cluster #N, since it is already in use for data in
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* cluster EXT4_B2C(sbi, map->m_lblk). We will then return 1 to
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* signal to ext4_ext_map_blocks() that map->m_pblk should be treated
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* as a new "allocated" block region. Otherwise, we will return 0 and
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* ext4_ext_map_blocks() will then allocate one or more new clusters
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* by calling ext4_mb_new_blocks().
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*/
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static int get_implied_cluster_alloc(struct ext4_sb_info *sbi,
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struct ext4_map_blocks *map,
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struct ext4_extent *ex,
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struct ext4_ext_path *path)
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{
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ext4_lblk_t c_offset = map->m_lblk & (sbi->s_cluster_ratio-1);
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ext4_lblk_t ex_cluster_start, ex_cluster_end;
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ext4_lblk_t rr_cluster_start, rr_cluster_end;
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ext4_lblk_t ee_block = le32_to_cpu(ex->ee_block);
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ext4_fsblk_t ee_start = ext4_ext_pblock(ex);
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unsigned short ee_len = ext4_ext_get_actual_len(ex);
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/* The extent passed in that we are trying to match */
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ex_cluster_start = EXT4_B2C(sbi, ee_block);
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ex_cluster_end = EXT4_B2C(sbi, ee_block + ee_len - 1);
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/* The requested region passed into ext4_map_blocks() */
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rr_cluster_start = EXT4_B2C(sbi, map->m_lblk);
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rr_cluster_end = EXT4_B2C(sbi, map->m_lblk + map->m_len - 1);
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if ((rr_cluster_start == ex_cluster_end) ||
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(rr_cluster_start == ex_cluster_start)) {
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if (rr_cluster_start == ex_cluster_end)
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ee_start += ee_len - 1;
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map->m_pblk = (ee_start & ~(sbi->s_cluster_ratio - 1)) +
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c_offset;
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map->m_len = min(map->m_len,
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(unsigned) sbi->s_cluster_ratio - c_offset);
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/*
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* Check for and handle this case:
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*
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* |--------- cluster # N-------------|
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* |------- extent ----|
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* |--- requested region ---|
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* |===========|
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*/
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if (map->m_lblk < ee_block)
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map->m_len = min(map->m_len, ee_block - map->m_lblk);
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/*
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* Check for the case where there is already another allocated
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* block to the right of 'ex' but before the end of the cluster.
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*
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* |------------- cluster # N-------------|
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* |----- ex -----| |---- ex_right ----|
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* |------ requested region ------|
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* |================|
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*/
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if (map->m_lblk > ee_block) {
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ext4_lblk_t next = ext4_ext_next_allocated_block(path);
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map->m_len = min(map->m_len, next - map->m_lblk);
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}
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return 1;
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}
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return 0;
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}
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/*
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* Block allocation/map/preallocation routine for extents based files
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*
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@ -3315,14 +3418,16 @@ int ext4_ext_map_blocks(handle_t *handle, struct inode *inode,
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struct ext4_map_blocks *map, int flags)
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{
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struct ext4_ext_path *path = NULL;
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struct ext4_extent newex, *ex;
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struct ext4_extent newex, *ex, *ex2;
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struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
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ext4_fsblk_t newblock = 0;
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int err = 0, depth, ret;
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unsigned int allocated = 0;
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int free_on_err = 0, err = 0, depth, ret;
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unsigned int allocated = 0, offset = 0;
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unsigned int punched_out = 0;
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unsigned int result = 0;
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struct ext4_allocation_request ar;
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ext4_io_end_t *io = EXT4_I(inode)->cur_aio_dio;
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ext4_lblk_t cluster_offset;
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struct ext4_map_blocks punch_map;
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ext_debug("blocks %u/%u requested for inode %lu\n",
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@ -3508,9 +3613,23 @@ int ext4_ext_map_blocks(handle_t *handle, struct inode *inode,
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ext4_ext_put_gap_in_cache(inode, path, map->m_lblk);
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goto out2;
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}
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/*
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* Okay, we need to do block allocation.
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*/
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newex.ee_block = cpu_to_le32(map->m_lblk);
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cluster_offset = map->m_lblk & (sbi->s_cluster_ratio-1);
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/*
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* If we are doing bigalloc, check to see if the extent returned
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* by ext4_ext_find_extent() implies a cluster we can use.
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*/
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if (cluster_offset && ex &&
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get_implied_cluster_alloc(sbi, map, ex, path)) {
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ar.len = allocated = map->m_len;
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newblock = map->m_pblk;
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goto got_allocated_blocks;
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}
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/* find neighbour allocated blocks */
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ar.lleft = map->m_lblk;
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@ -3518,10 +3637,20 @@ int ext4_ext_map_blocks(handle_t *handle, struct inode *inode,
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if (err)
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goto out2;
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ar.lright = map->m_lblk;
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err = ext4_ext_search_right(inode, path, &ar.lright, &ar.pright);
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ex2 = NULL;
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err = ext4_ext_search_right(inode, path, &ar.lright, &ar.pright, &ex2);
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if (err)
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goto out2;
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/* Check if the extent after searching to the right implies a
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* cluster we can use. */
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if ((sbi->s_cluster_ratio > 1) && ex2 &&
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get_implied_cluster_alloc(sbi, map, ex2, path)) {
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ar.len = allocated = map->m_len;
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newblock = map->m_pblk;
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goto got_allocated_blocks;
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}
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/*
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* See if request is beyond maximum number of blocks we can have in
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* a single extent. For an initialized extent this limit is
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@ -3536,9 +3665,8 @@ int ext4_ext_map_blocks(handle_t *handle, struct inode *inode,
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map->m_len = EXT_UNINIT_MAX_LEN;
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/* Check if we can really insert (m_lblk)::(m_lblk + m_len) extent */
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newex.ee_block = cpu_to_le32(map->m_lblk);
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newex.ee_len = cpu_to_le16(map->m_len);
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err = ext4_ext_check_overlap(inode, &newex, path);
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err = ext4_ext_check_overlap(sbi, inode, &newex, path);
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if (err)
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allocated = ext4_ext_get_actual_len(&newex);
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else
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@ -3548,7 +3676,18 @@ int ext4_ext_map_blocks(handle_t *handle, struct inode *inode,
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ar.inode = inode;
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ar.goal = ext4_ext_find_goal(inode, path, map->m_lblk);
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ar.logical = map->m_lblk;
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ar.len = allocated;
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/*
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* We calculate the offset from the beginning of the cluster
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* for the logical block number, since when we allocate a
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* physical cluster, the physical block should start at the
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* same offset from the beginning of the cluster. This is
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* needed so that future calls to get_implied_cluster_alloc()
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* work correctly.
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*/
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offset = map->m_lblk & (sbi->s_cluster_ratio - 1);
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ar.len = EXT4_NUM_B2C(sbi, offset+allocated);
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ar.goal -= offset;
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ar.logical -= offset;
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if (S_ISREG(inode->i_mode))
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ar.flags = EXT4_MB_HINT_DATA;
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else
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@ -3561,9 +3700,14 @@ int ext4_ext_map_blocks(handle_t *handle, struct inode *inode,
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goto out2;
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ext_debug("allocate new block: goal %llu, found %llu/%u\n",
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ar.goal, newblock, allocated);
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free_on_err = 1;
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ar.len = EXT4_C2B(sbi, ar.len) - offset;
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if (ar.len > allocated)
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ar.len = allocated;
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got_allocated_blocks:
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/* try to insert new extent into found leaf and return */
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ext4_ext_store_pblock(&newex, newblock);
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ext4_ext_store_pblock(&newex, newblock + offset);
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newex.ee_len = cpu_to_le16(ar.len);
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/* Mark uninitialized */
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if (flags & EXT4_GET_BLOCKS_UNINIT_EXT){
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@ -3591,7 +3735,7 @@ int ext4_ext_map_blocks(handle_t *handle, struct inode *inode,
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if (!err)
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err = ext4_ext_insert_extent(handle, inode, path,
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&newex, flags);
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if (err) {
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if (err && free_on_err) {
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int fb_flags = flags & EXT4_GET_BLOCKS_DELALLOC_RESERVE ?
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EXT4_FREE_BLOCKS_NO_QUOT_UPDATE : 0;
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/* free data blocks we just allocated */
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@ -4115,7 +4259,6 @@ found_delayed_extent:
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return EXT_BREAK;
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return EXT_CONTINUE;
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}
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/* fiemap flags we can handle specified here */
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#define EXT4_FIEMAP_FLAGS (FIEMAP_FLAG_SYNC|FIEMAP_FLAG_XATTR)
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