提交 4d33b1ef 编写于 作者: T Theodore Ts'o

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: N"Theodore Ts'o" <tytso@mit.edu>
上级 84130193
......@@ -1270,7 +1270,8 @@ static int ext4_ext_search_left(struct inode *inode,
*/
static int ext4_ext_search_right(struct inode *inode,
struct ext4_ext_path *path,
ext4_lblk_t *logical, ext4_fsblk_t *phys)
ext4_lblk_t *logical, ext4_fsblk_t *phys,
struct ext4_extent **ret_ex)
{
struct buffer_head *bh = NULL;
struct ext4_extent_header *eh;
......@@ -1312,9 +1313,7 @@ static int ext4_ext_search_right(struct inode *inode,
return -EIO;
}
}
*logical = le32_to_cpu(ex->ee_block);
*phys = ext4_ext_pblock(ex);
return 0;
goto found_extent;
}
if (unlikely(*logical < (le32_to_cpu(ex->ee_block) + ee_len))) {
......@@ -1327,9 +1326,7 @@ static int ext4_ext_search_right(struct inode *inode,
if (ex != EXT_LAST_EXTENT(path[depth].p_hdr)) {
/* next allocated block in this leaf */
ex++;
*logical = le32_to_cpu(ex->ee_block);
*phys = ext4_ext_pblock(ex);
return 0;
goto found_extent;
}
/* go up and search for index to the right */
......@@ -1372,9 +1369,12 @@ static int ext4_ext_search_right(struct inode *inode,
return -EIO;
}
ex = EXT_FIRST_EXTENT(eh);
found_extent:
*logical = le32_to_cpu(ex->ee_block);
*phys = ext4_ext_pblock(ex);
put_bh(bh);
*ret_ex = ex;
if (bh)
put_bh(bh);
return 0;
}
......@@ -1627,7 +1627,8 @@ static int ext4_ext_try_to_merge(struct inode *inode,
* such that there will be no overlap, and then returns 1.
* If there is no overlap found, it returns 0.
*/
static unsigned int ext4_ext_check_overlap(struct inode *inode,
static unsigned int ext4_ext_check_overlap(struct ext4_sb_info *sbi,
struct inode *inode,
struct ext4_extent *newext,
struct ext4_ext_path *path)
{
......@@ -1641,6 +1642,7 @@ static unsigned int ext4_ext_check_overlap(struct inode *inode,
if (!path[depth].p_ext)
goto out;
b2 = le32_to_cpu(path[depth].p_ext->ee_block);
b2 &= ~(sbi->s_cluster_ratio - 1);
/*
* get the next allocated block if the extent in the path
......@@ -1650,6 +1652,7 @@ static unsigned int ext4_ext_check_overlap(struct inode *inode,
b2 = ext4_ext_next_allocated_block(path);
if (b2 == EXT_MAX_BLOCKS)
goto out;
b2 &= ~(sbi->s_cluster_ratio - 1);
}
/* check for wrap through zero on extent logical start block*/
......@@ -3293,6 +3296,106 @@ ext4_ext_handle_uninitialized_extents(handle_t *handle, struct inode *inode,
return err ? err : allocated;
}
/*
* get_implied_cluster_alloc - check to see if the requested
* allocation (in the map structure) overlaps with a cluster already
* allocated in an extent.
* @sbi The ext4-specific superblock structure
* @map The requested lblk->pblk mapping
* @ex The extent structure which might contain an implied
* cluster allocation
*
* This function is called by ext4_ext_map_blocks() after we failed to
* find blocks that were already in the inode's extent tree. Hence,
* we know that the beginning of the requested region cannot overlap
* the extent from the inode's extent tree. There are three cases we
* want to catch. The first is this case:
*
* |--- cluster # N--|
* |--- extent ---| |---- requested region ---|
* |==========|
*
* The second case that we need to test for is this one:
*
* |--------- cluster # N ----------------|
* |--- requested region --| |------- extent ----|
* |=======================|
*
* The third case is when the requested region lies between two extents
* within the same cluster:
* |------------- cluster # N-------------|
* |----- ex -----| |---- ex_right ----|
* |------ requested region ------|
* |================|
*
* In each of the above cases, we need to set the map->m_pblk and
* map->m_len so it corresponds to the return the extent labelled as
* "|====|" from cluster #N, since it is already in use for data in
* cluster EXT4_B2C(sbi, map->m_lblk). We will then return 1 to
* signal to ext4_ext_map_blocks() that map->m_pblk should be treated
* as a new "allocated" block region. Otherwise, we will return 0 and
* ext4_ext_map_blocks() will then allocate one or more new clusters
* by calling ext4_mb_new_blocks().
*/
static int get_implied_cluster_alloc(struct ext4_sb_info *sbi,
struct ext4_map_blocks *map,
struct ext4_extent *ex,
struct ext4_ext_path *path)
{
ext4_lblk_t c_offset = map->m_lblk & (sbi->s_cluster_ratio-1);
ext4_lblk_t ex_cluster_start, ex_cluster_end;
ext4_lblk_t rr_cluster_start, rr_cluster_end;
ext4_lblk_t ee_block = le32_to_cpu(ex->ee_block);
ext4_fsblk_t ee_start = ext4_ext_pblock(ex);
unsigned short ee_len = ext4_ext_get_actual_len(ex);
/* The extent passed in that we are trying to match */
ex_cluster_start = EXT4_B2C(sbi, ee_block);
ex_cluster_end = EXT4_B2C(sbi, ee_block + ee_len - 1);
/* The requested region passed into ext4_map_blocks() */
rr_cluster_start = EXT4_B2C(sbi, map->m_lblk);
rr_cluster_end = EXT4_B2C(sbi, map->m_lblk + map->m_len - 1);
if ((rr_cluster_start == ex_cluster_end) ||
(rr_cluster_start == ex_cluster_start)) {
if (rr_cluster_start == ex_cluster_end)
ee_start += ee_len - 1;
map->m_pblk = (ee_start & ~(sbi->s_cluster_ratio - 1)) +
c_offset;
map->m_len = min(map->m_len,
(unsigned) sbi->s_cluster_ratio - c_offset);
/*
* Check for and handle this case:
*
* |--------- cluster # N-------------|
* |------- extent ----|
* |--- requested region ---|
* |===========|
*/
if (map->m_lblk < ee_block)
map->m_len = min(map->m_len, ee_block - map->m_lblk);
/*
* Check for the case where there is already another allocated
* block to the right of 'ex' but before the end of the cluster.
*
* |------------- cluster # N-------------|
* |----- ex -----| |---- ex_right ----|
* |------ requested region ------|
* |================|
*/
if (map->m_lblk > ee_block) {
ext4_lblk_t next = ext4_ext_next_allocated_block(path);
map->m_len = min(map->m_len, next - map->m_lblk);
}
return 1;
}
return 0;
}
/*
* Block allocation/map/preallocation routine for extents based files
*
......@@ -3315,14 +3418,16 @@ int ext4_ext_map_blocks(handle_t *handle, struct inode *inode,
struct ext4_map_blocks *map, int flags)
{
struct ext4_ext_path *path = NULL;
struct ext4_extent newex, *ex;
struct ext4_extent newex, *ex, *ex2;
struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
ext4_fsblk_t newblock = 0;
int err = 0, depth, ret;
unsigned int allocated = 0;
int free_on_err = 0, err = 0, depth, ret;
unsigned int allocated = 0, offset = 0;
unsigned int punched_out = 0;
unsigned int result = 0;
struct ext4_allocation_request ar;
ext4_io_end_t *io = EXT4_I(inode)->cur_aio_dio;
ext4_lblk_t cluster_offset;
struct ext4_map_blocks punch_map;
ext_debug("blocks %u/%u requested for inode %lu\n",
......@@ -3508,9 +3613,23 @@ int ext4_ext_map_blocks(handle_t *handle, struct inode *inode,
ext4_ext_put_gap_in_cache(inode, path, map->m_lblk);
goto out2;
}
/*
* Okay, we need to do block allocation.
*/
newex.ee_block = cpu_to_le32(map->m_lblk);
cluster_offset = map->m_lblk & (sbi->s_cluster_ratio-1);
/*
* If we are doing bigalloc, check to see if the extent returned
* by ext4_ext_find_extent() implies a cluster we can use.
*/
if (cluster_offset && ex &&
get_implied_cluster_alloc(sbi, map, ex, path)) {
ar.len = allocated = map->m_len;
newblock = map->m_pblk;
goto got_allocated_blocks;
}
/* find neighbour allocated blocks */
ar.lleft = map->m_lblk;
......@@ -3518,10 +3637,20 @@ int ext4_ext_map_blocks(handle_t *handle, struct inode *inode,
if (err)
goto out2;
ar.lright = map->m_lblk;
err = ext4_ext_search_right(inode, path, &ar.lright, &ar.pright);
ex2 = NULL;
err = ext4_ext_search_right(inode, path, &ar.lright, &ar.pright, &ex2);
if (err)
goto out2;
/* Check if the extent after searching to the right implies a
* cluster we can use. */
if ((sbi->s_cluster_ratio > 1) && ex2 &&
get_implied_cluster_alloc(sbi, map, ex2, path)) {
ar.len = allocated = map->m_len;
newblock = map->m_pblk;
goto got_allocated_blocks;
}
/*
* See if request is beyond maximum number of blocks we can have in
* a single extent. For an initialized extent this limit is
......@@ -3536,9 +3665,8 @@ int ext4_ext_map_blocks(handle_t *handle, struct inode *inode,
map->m_len = EXT_UNINIT_MAX_LEN;
/* Check if we can really insert (m_lblk)::(m_lblk + m_len) extent */
newex.ee_block = cpu_to_le32(map->m_lblk);
newex.ee_len = cpu_to_le16(map->m_len);
err = ext4_ext_check_overlap(inode, &newex, path);
err = ext4_ext_check_overlap(sbi, inode, &newex, path);
if (err)
allocated = ext4_ext_get_actual_len(&newex);
else
......@@ -3548,7 +3676,18 @@ int ext4_ext_map_blocks(handle_t *handle, struct inode *inode,
ar.inode = inode;
ar.goal = ext4_ext_find_goal(inode, path, map->m_lblk);
ar.logical = map->m_lblk;
ar.len = allocated;
/*
* We calculate the offset from the beginning of the cluster
* for the logical block number, since when we allocate a
* physical cluster, the physical block should start at the
* same offset from the beginning of the cluster. This is
* needed so that future calls to get_implied_cluster_alloc()
* work correctly.
*/
offset = map->m_lblk & (sbi->s_cluster_ratio - 1);
ar.len = EXT4_NUM_B2C(sbi, offset+allocated);
ar.goal -= offset;
ar.logical -= offset;
if (S_ISREG(inode->i_mode))
ar.flags = EXT4_MB_HINT_DATA;
else
......@@ -3561,9 +3700,14 @@ int ext4_ext_map_blocks(handle_t *handle, struct inode *inode,
goto out2;
ext_debug("allocate new block: goal %llu, found %llu/%u\n",
ar.goal, newblock, allocated);
free_on_err = 1;
ar.len = EXT4_C2B(sbi, ar.len) - offset;
if (ar.len > allocated)
ar.len = allocated;
got_allocated_blocks:
/* try to insert new extent into found leaf and return */
ext4_ext_store_pblock(&newex, newblock);
ext4_ext_store_pblock(&newex, newblock + offset);
newex.ee_len = cpu_to_le16(ar.len);
/* Mark uninitialized */
if (flags & EXT4_GET_BLOCKS_UNINIT_EXT){
......@@ -3591,7 +3735,7 @@ int ext4_ext_map_blocks(handle_t *handle, struct inode *inode,
if (!err)
err = ext4_ext_insert_extent(handle, inode, path,
&newex, flags);
if (err) {
if (err && free_on_err) {
int fb_flags = flags & EXT4_GET_BLOCKS_DELALLOC_RESERVE ?
EXT4_FREE_BLOCKS_NO_QUOT_UPDATE : 0;
/* free data blocks we just allocated */
......@@ -4115,7 +4259,6 @@ static int ext4_ext_fiemap_cb(struct inode *inode, ext4_lblk_t next,
return EXT_BREAK;
return EXT_CONTINUE;
}
/* fiemap flags we can handle specified here */
#define EXT4_FIEMAP_FLAGS (FIEMAP_FLAG_SYNC|FIEMAP_FLAG_XATTR)
......
Markdown is supported
0% .
You are about to add 0 people to the discussion. Proceed with caution.
先完成此消息的编辑!
想要评论请 注册