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kernel-ark/fs/ext4/extents_status.c
Zheng Liu d3922a777f ext4: improve extent cache shrink mechanism to avoid to burn CPU time 
Now we maintain an proper in-order LRU list in ext4 to reclaim entries
from extent status tree when we are under heavy memory pressure.  For
keeping this order, a spin lock is used to protect this list.  But this
lock burns a lot of CPU time.  We can use the following steps to trigger
it.

  % cd /dev/shm
  % dd if=/dev/zero of=ext4-img bs=1M count=2k
  % mkfs.ext4 ext4-img
  % mount -t ext4 -o loop ext4-img /mnt
  % cd /mnt
  % for ((i=0;i<160;i++)); do truncate -s 64g $i; done
  % for ((i=0;i<160;i++)); do cp $i /dev/null &; done
  % perf record -a -g
  % perf report

This commit tries to fix this problem.  Now a new member called
i_touch_when is added into ext4_inode_info to record the last access
time for an inode.  Meanwhile we never need to keep a proper in-order
LRU list.  So this can avoid to burns some CPU time.  When we try to
reclaim some entries from extent status tree, we use list_sort() to get
a proper in-order list.  Then we traverse this list to discard some
entries.  In ext4_sb_info, we use s_es_last_sorted to record the last
time of sorting this list.  When we traverse the list, we skip the inode
that is newer than this time, and move this inode to the tail of LRU
list.  When the head of the list is newer than s_es_last_sorted, we will
sort the LRU list again.

In this commit, we break the loop if s_extent_cache_cnt == 0 because
that means that all extents in extent status tree have been reclaimed.

Meanwhile in this commit, ext4_es_{un}register_shrinker()'s prototype is
changed to save a local variable in these functions.

Reported-by: Dave Hansen <dave.hansen@intel.com>
Signed-off-by: Zheng Liu <wenqing.lz@taobao.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
2013-07-01 08:12:37 -04:00

1035 lines
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/*
* fs/ext4/extents_status.c
*
* Written by Yongqiang Yang <xiaoqiangnk@gmail.com>
* Modified by
* Allison Henderson <achender@linux.vnet.ibm.com>
* Hugh Dickins <hughd@google.com>
* Zheng Liu <wenqing.lz@taobao.com>
*
* Ext4 extents status tree core functions.
*/
#include <linux/rbtree.h>
#include <linux/list_sort.h>
#include "ext4.h"
#include "extents_status.h"
#include "ext4_extents.h"
#include <trace/events/ext4.h>
/*
* According to previous discussion in Ext4 Developer Workshop, we
* will introduce a new structure called io tree to track all extent
* status in order to solve some problems that we have met
* (e.g. Reservation space warning), and provide extent-level locking.
* Delay extent tree is the first step to achieve this goal. It is
* original built by Yongqiang Yang. At that time it is called delay
* extent tree, whose goal is only track delayed extents in memory to
* simplify the implementation of fiemap and bigalloc, and introduce
* lseek SEEK_DATA/SEEK_HOLE support. That is why it is still called
* delay extent tree at the first commit. But for better understand
* what it does, it has been rename to extent status tree.
*
* Step1:
* Currently the first step has been done. All delayed extents are
* tracked in the tree. It maintains the delayed extent when a delayed
* allocation is issued, and the delayed extent is written out or
* invalidated. Therefore the implementation of fiemap and bigalloc
* are simplified, and SEEK_DATA/SEEK_HOLE are introduced.
*
* The following comment describes the implemenmtation of extent
* status tree and future works.
*
* Step2:
* In this step all extent status are tracked by extent status tree.
* Thus, we can first try to lookup a block mapping in this tree before
* finding it in extent tree. Hence, single extent cache can be removed
* because extent status tree can do a better job. Extents in status
* tree are loaded on-demand. Therefore, the extent status tree may not
* contain all of the extents in a file. Meanwhile we define a shrinker
* to reclaim memory from extent status tree because fragmented extent
* tree will make status tree cost too much memory. written/unwritten/-
* hole extents in the tree will be reclaimed by this shrinker when we
* are under high memory pressure. Delayed extents will not be
* reclimed because fiemap, bigalloc, and seek_data/hole need it.
*/
/*
* Extent status tree implementation for ext4.
*
*
* ==========================================================================
* Extent status tree tracks all extent status.
*
* 1. Why we need to implement extent status tree?
*
* Without extent status tree, ext4 identifies a delayed extent by looking
* up page cache, this has several deficiencies - complicated, buggy,
* and inefficient code.
*
* FIEMAP, SEEK_HOLE/DATA, bigalloc, and writeout all need to know if a
* block or a range of blocks are belonged to a delayed extent.
*
* Let us have a look at how they do without extent status tree.
* -- FIEMAP
* FIEMAP looks up page cache to identify delayed allocations from holes.
*
* -- SEEK_HOLE/DATA
* SEEK_HOLE/DATA has the same problem as FIEMAP.
*
* -- bigalloc
* bigalloc looks up page cache to figure out if a block is
* already under delayed allocation or not to determine whether
* quota reserving is needed for the cluster.
*
* -- writeout
* Writeout looks up whole page cache to see if a buffer is
* mapped, If there are not very many delayed buffers, then it is
* time comsuming.
*
* With extent status tree implementation, FIEMAP, SEEK_HOLE/DATA,
* bigalloc and writeout can figure out if a block or a range of
* blocks is under delayed allocation(belonged to a delayed extent) or
* not by searching the extent tree.
*
*
* ==========================================================================
* 2. Ext4 extent status tree impelmentation
*
* -- extent
* A extent is a range of blocks which are contiguous logically and
* physically. Unlike extent in extent tree, this extent in ext4 is
* a in-memory struct, there is no corresponding on-disk data. There
* is no limit on length of extent, so an extent can contain as many
* blocks as they are contiguous logically and physically.
*
* -- extent status tree
* Every inode has an extent status tree and all allocation blocks
* are added to the tree with different status. The extent in the
* tree are ordered by logical block no.
*
* -- operations on a extent status tree
* There are three important operations on a delayed extent tree: find
* next extent, adding a extent(a range of blocks) and removing a extent.
*
* -- race on a extent status tree
* Extent status tree is protected by inode->i_es_lock.
*
* -- memory consumption
* Fragmented extent tree will make extent status tree cost too much
* memory. Hence, we will reclaim written/unwritten/hole extents from
* the tree under a heavy memory pressure.
*
*
* ==========================================================================
* 3. Performance analysis
*
* -- overhead
* 1. There is a cache extent for write access, so if writes are
* not very random, adding space operaions are in O(1) time.
*
* -- gain
* 2. Code is much simpler, more readable, more maintainable and
* more efficient.
*
*
* ==========================================================================
* 4. TODO list
*
* -- Refactor delayed space reservation
*
* -- Extent-level locking
*/
static struct kmem_cache *ext4_es_cachep;
static int __es_insert_extent(struct inode *inode, struct extent_status *newes);
static int __es_remove_extent(struct inode *inode, ext4_lblk_t lblk,
ext4_lblk_t end);
static int __es_try_to_reclaim_extents(struct ext4_inode_info *ei,
int nr_to_scan);
int __init ext4_init_es(void)
{
ext4_es_cachep = kmem_cache_create("ext4_extent_status",
sizeof(struct extent_status),
0, (SLAB_RECLAIM_ACCOUNT), NULL);
if (ext4_es_cachep == NULL)
return -ENOMEM;
return 0;
}
void ext4_exit_es(void)
{
if (ext4_es_cachep)
kmem_cache_destroy(ext4_es_cachep);
}
void ext4_es_init_tree(struct ext4_es_tree *tree)
{
tree->root = RB_ROOT;
tree->cache_es = NULL;
}
#ifdef ES_DEBUG__
static void ext4_es_print_tree(struct inode *inode)
{
struct ext4_es_tree *tree;
struct rb_node *node;
printk(KERN_DEBUG "status extents for inode %lu:", inode->i_ino);
tree = &EXT4_I(inode)->i_es_tree;
node = rb_first(&tree->root);
while (node) {
struct extent_status *es;
es = rb_entry(node, struct extent_status, rb_node);
printk(KERN_DEBUG " [%u/%u) %llu %llx",
es->es_lblk, es->es_len,
ext4_es_pblock(es), ext4_es_status(es));
node = rb_next(node);
}
printk(KERN_DEBUG "\n");
}
#else
#define ext4_es_print_tree(inode)
#endif
static inline ext4_lblk_t ext4_es_end(struct extent_status *es)
{
BUG_ON(es->es_lblk + es->es_len < es->es_lblk);
return es->es_lblk + es->es_len - 1;
}
/*
* search through the tree for an delayed extent with a given offset. If
* it can't be found, try to find next extent.
*/
static struct extent_status *__es_tree_search(struct rb_root *root,
ext4_lblk_t lblk)
{
struct rb_node *node = root->rb_node;
struct extent_status *es = NULL;
while (node) {
es = rb_entry(node, struct extent_status, rb_node);
if (lblk < es->es_lblk)
node = node->rb_left;
else if (lblk > ext4_es_end(es))
node = node->rb_right;
else
return es;
}
if (es && lblk < es->es_lblk)
return es;
if (es && lblk > ext4_es_end(es)) {
node = rb_next(&es->rb_node);
return node ? rb_entry(node, struct extent_status, rb_node) :
NULL;
}
return NULL;
}
/*
* ext4_es_find_delayed_extent_range: find the 1st delayed extent covering
* @es->lblk if it exists, otherwise, the next extent after @es->lblk.
*
* @inode: the inode which owns delayed extents
* @lblk: the offset where we start to search
* @end: the offset where we stop to search
* @es: delayed extent that we found
*/
void ext4_es_find_delayed_extent_range(struct inode *inode,
ext4_lblk_t lblk, ext4_lblk_t end,
struct extent_status *es)
{
struct ext4_es_tree *tree = NULL;
struct extent_status *es1 = NULL;
struct rb_node *node;
BUG_ON(es == NULL);
BUG_ON(end < lblk);
trace_ext4_es_find_delayed_extent_range_enter(inode, lblk);
read_lock(&EXT4_I(inode)->i_es_lock);
tree = &EXT4_I(inode)->i_es_tree;
/* find extent in cache firstly */
es->es_lblk = es->es_len = es->es_pblk = 0;
if (tree->cache_es) {
es1 = tree->cache_es;
if (in_range(lblk, es1->es_lblk, es1->es_len)) {
es_debug("%u cached by [%u/%u) %llu %llx\n",
lblk, es1->es_lblk, es1->es_len,
ext4_es_pblock(es1), ext4_es_status(es1));
goto out;
}
}
es1 = __es_tree_search(&tree->root, lblk);
out:
if (es1 && !ext4_es_is_delayed(es1)) {
while ((node = rb_next(&es1->rb_node)) != NULL) {
es1 = rb_entry(node, struct extent_status, rb_node);
if (es1->es_lblk > end) {
es1 = NULL;
break;
}
if (ext4_es_is_delayed(es1))
break;
}
}
if (es1 && ext4_es_is_delayed(es1)) {
tree->cache_es = es1;
es->es_lblk = es1->es_lblk;
es->es_len = es1->es_len;
es->es_pblk = es1->es_pblk;
}
read_unlock(&EXT4_I(inode)->i_es_lock);
trace_ext4_es_find_delayed_extent_range_exit(inode, es);
}
static struct extent_status *
ext4_es_alloc_extent(struct inode *inode, ext4_lblk_t lblk, ext4_lblk_t len,
ext4_fsblk_t pblk)
{
struct extent_status *es;
es = kmem_cache_alloc(ext4_es_cachep, GFP_ATOMIC);
if (es == NULL)
return NULL;
es->es_lblk = lblk;
es->es_len = len;
es->es_pblk = pblk;
/*
* We don't count delayed extent because we never try to reclaim them
*/
if (!ext4_es_is_delayed(es)) {
EXT4_I(inode)->i_es_lru_nr++;
percpu_counter_inc(&EXT4_SB(inode->i_sb)->s_extent_cache_cnt);
}
return es;
}
static void ext4_es_free_extent(struct inode *inode, struct extent_status *es)
{
/* Decrease the lru counter when this es is not delayed */
if (!ext4_es_is_delayed(es)) {
BUG_ON(EXT4_I(inode)->i_es_lru_nr == 0);
EXT4_I(inode)->i_es_lru_nr--;
percpu_counter_dec(&EXT4_SB(inode->i_sb)->s_extent_cache_cnt);
}
kmem_cache_free(ext4_es_cachep, es);
}
/*
* Check whether or not two extents can be merged
* Condition:
* - logical block number is contiguous
* - physical block number is contiguous
* - status is equal
*/
static int ext4_es_can_be_merged(struct extent_status *es1,
struct extent_status *es2)
{
if (ext4_es_status(es1) != ext4_es_status(es2))
return 0;
if (((__u64) es1->es_len) + es2->es_len > 0xFFFFFFFFULL)
return 0;
if (((__u64) es1->es_lblk) + es1->es_len != es2->es_lblk)
return 0;
if ((ext4_es_is_written(es1) || ext4_es_is_unwritten(es1)) &&
(ext4_es_pblock(es1) + es1->es_len == ext4_es_pblock(es2)))
return 1;
if (ext4_es_is_hole(es1))
return 1;
/* we need to check delayed extent is without unwritten status */
if (ext4_es_is_delayed(es1) && !ext4_es_is_unwritten(es1))
return 1;
return 0;
}
static struct extent_status *
ext4_es_try_to_merge_left(struct inode *inode, struct extent_status *es)
{
struct ext4_es_tree *tree = &EXT4_I(inode)->i_es_tree;
struct extent_status *es1;
struct rb_node *node;
node = rb_prev(&es->rb_node);
if (!node)
return es;
es1 = rb_entry(node, struct extent_status, rb_node);
if (ext4_es_can_be_merged(es1, es)) {
es1->es_len += es->es_len;
rb_erase(&es->rb_node, &tree->root);
ext4_es_free_extent(inode, es);
es = es1;
}
return es;
}
static struct extent_status *
ext4_es_try_to_merge_right(struct inode *inode, struct extent_status *es)
{
struct ext4_es_tree *tree = &EXT4_I(inode)->i_es_tree;
struct extent_status *es1;
struct rb_node *node;
node = rb_next(&es->rb_node);
if (!node)
return es;
es1 = rb_entry(node, struct extent_status, rb_node);
if (ext4_es_can_be_merged(es, es1)) {
es->es_len += es1->es_len;
rb_erase(node, &tree->root);
ext4_es_free_extent(inode, es1);
}
return es;
}
#ifdef ES_AGGRESSIVE_TEST
static void ext4_es_insert_extent_ext_check(struct inode *inode,
struct extent_status *es)
{
struct ext4_ext_path *path = NULL;
struct ext4_extent *ex;
ext4_lblk_t ee_block;
ext4_fsblk_t ee_start;
unsigned short ee_len;
int depth, ee_status, es_status;
path = ext4_ext_find_extent(inode, es->es_lblk, NULL);
if (IS_ERR(path))
return;
depth = ext_depth(inode);
ex = path[depth].p_ext;
if (ex) {
ee_block = le32_to_cpu(ex->ee_block);
ee_start = ext4_ext_pblock(ex);
ee_len = ext4_ext_get_actual_len(ex);
ee_status = ext4_ext_is_uninitialized(ex) ? 1 : 0;
es_status = ext4_es_is_unwritten(es) ? 1 : 0;
/*
* Make sure ex and es are not overlap when we try to insert
* a delayed/hole extent.
*/
if (!ext4_es_is_written(es) && !ext4_es_is_unwritten(es)) {
if (in_range(es->es_lblk, ee_block, ee_len)) {
pr_warn("ES insert assertation failed for "
"inode: %lu we can find an extent "
"at block [%d/%d/%llu/%c], but we "
"want to add an delayed/hole extent "
"[%d/%d/%llu/%llx]\n",
inode->i_ino, ee_block, ee_len,
ee_start, ee_status ? 'u' : 'w',
es->es_lblk, es->es_len,
ext4_es_pblock(es), ext4_es_status(es));
}
goto out;
}
/*
* We don't check ee_block == es->es_lblk, etc. because es
* might be a part of whole extent, vice versa.
*/
if (es->es_lblk < ee_block ||
ext4_es_pblock(es) != ee_start + es->es_lblk - ee_block) {
pr_warn("ES insert assertation failed for inode: %lu "
"ex_status [%d/%d/%llu/%c] != "
"es_status [%d/%d/%llu/%c]\n", inode->i_ino,
ee_block, ee_len, ee_start,
ee_status ? 'u' : 'w', es->es_lblk, es->es_len,
ext4_es_pblock(es), es_status ? 'u' : 'w');
goto out;
}
if (ee_status ^ es_status) {
pr_warn("ES insert assertation failed for inode: %lu "
"ex_status [%d/%d/%llu/%c] != "
"es_status [%d/%d/%llu/%c]\n", inode->i_ino,
ee_block, ee_len, ee_start,
ee_status ? 'u' : 'w', es->es_lblk, es->es_len,
ext4_es_pblock(es), es_status ? 'u' : 'w');
}
} else {
/*
* We can't find an extent on disk. So we need to make sure
* that we don't want to add an written/unwritten extent.
*/
if (!ext4_es_is_delayed(es) && !ext4_es_is_hole(es)) {
pr_warn("ES insert assertation failed for inode: %lu "
"can't find an extent at block %d but we want "
"to add an written/unwritten extent "
"[%d/%d/%llu/%llx]\n", inode->i_ino,
es->es_lblk, es->es_lblk, es->es_len,
ext4_es_pblock(es), ext4_es_status(es));
}
}
out:
if (path) {
ext4_ext_drop_refs(path);
kfree(path);
}
}
static void ext4_es_insert_extent_ind_check(struct inode *inode,
struct extent_status *es)
{
struct ext4_map_blocks map;
int retval;
/*
* Here we call ext4_ind_map_blocks to lookup a block mapping because
* 'Indirect' structure is defined in indirect.c. So we couldn't
* access direct/indirect tree from outside. It is too dirty to define
* this function in indirect.c file.
*/
map.m_lblk = es->es_lblk;
map.m_len = es->es_len;
retval = ext4_ind_map_blocks(NULL, inode, &map, 0);
if (retval > 0) {
if (ext4_es_is_delayed(es) || ext4_es_is_hole(es)) {
/*
* We want to add a delayed/hole extent but this
* block has been allocated.
*/
pr_warn("ES insert assertation failed for inode: %lu "
"We can find blocks but we want to add a "
"delayed/hole extent [%d/%d/%llu/%llx]\n",
inode->i_ino, es->es_lblk, es->es_len,
ext4_es_pblock(es), ext4_es_status(es));
return;
} else if (ext4_es_is_written(es)) {
if (retval != es->es_len) {
pr_warn("ES insert assertation failed for "
"inode: %lu retval %d != es_len %d\n",
inode->i_ino, retval, es->es_len);
return;
}
if (map.m_pblk != ext4_es_pblock(es)) {
pr_warn("ES insert assertation failed for "
"inode: %lu m_pblk %llu != "
"es_pblk %llu\n",
inode->i_ino, map.m_pblk,
ext4_es_pblock(es));
return;
}
} else {
/*
* We don't need to check unwritten extent because
* indirect-based file doesn't have it.
*/
BUG_ON(1);
}
} else if (retval == 0) {
if (ext4_es_is_written(es)) {
pr_warn("ES insert assertation failed for inode: %lu "
"We can't find the block but we want to add "
"an written extent [%d/%d/%llu/%llx]\n",
inode->i_ino, es->es_lblk, es->es_len,
ext4_es_pblock(es), ext4_es_status(es));
return;
}
}
}
static inline void ext4_es_insert_extent_check(struct inode *inode,
struct extent_status *es)
{
/*
* We don't need to worry about the race condition because
* caller takes i_data_sem locking.
*/
BUG_ON(!rwsem_is_locked(&EXT4_I(inode)->i_data_sem));
if (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))
ext4_es_insert_extent_ext_check(inode, es);
else
ext4_es_insert_extent_ind_check(inode, es);
}
#else
static inline void ext4_es_insert_extent_check(struct inode *inode,
struct extent_status *es)
{
}
#endif
static int __es_insert_extent(struct inode *inode, struct extent_status *newes)
{
struct ext4_es_tree *tree = &EXT4_I(inode)->i_es_tree;
struct rb_node **p = &tree->root.rb_node;
struct rb_node *parent = NULL;
struct extent_status *es;
while (*p) {
parent = *p;
es = rb_entry(parent, struct extent_status, rb_node);
if (newes->es_lblk < es->es_lblk) {
if (ext4_es_can_be_merged(newes, es)) {
/*
* Here we can modify es_lblk directly
* because it isn't overlapped.
*/
es->es_lblk = newes->es_lblk;
es->es_len += newes->es_len;
if (ext4_es_is_written(es) ||
ext4_es_is_unwritten(es))
ext4_es_store_pblock(es,
newes->es_pblk);
es = ext4_es_try_to_merge_left(inode, es);
goto out;
}
p = &(*p)->rb_left;
} else if (newes->es_lblk > ext4_es_end(es)) {
if (ext4_es_can_be_merged(es, newes)) {
es->es_len += newes->es_len;
es = ext4_es_try_to_merge_right(inode, es);
goto out;
}
p = &(*p)->rb_right;
} else {
BUG_ON(1);
return -EINVAL;
}
}
es = ext4_es_alloc_extent(inode, newes->es_lblk, newes->es_len,
newes->es_pblk);
if (!es)
return -ENOMEM;
rb_link_node(&es->rb_node, parent, p);
rb_insert_color(&es->rb_node, &tree->root);
out:
tree->cache_es = es;
return 0;
}
/*
* ext4_es_insert_extent() adds a space to a extent status tree.
*
* ext4_es_insert_extent is called by ext4_da_write_begin and
* ext4_es_remove_extent.
*
* Return 0 on success, error code on failure.
*/
int ext4_es_insert_extent(struct inode *inode, ext4_lblk_t lblk,
ext4_lblk_t len, ext4_fsblk_t pblk,
unsigned long long status)
{
struct extent_status newes;
ext4_lblk_t end = lblk + len - 1;
int err = 0;
es_debug("add [%u/%u) %llu %llx to extent status tree of inode %lu\n",
lblk, len, pblk, status, inode->i_ino);
if (!len)
return 0;
BUG_ON(end < lblk);
newes.es_lblk = lblk;
newes.es_len = len;
ext4_es_store_pblock(&newes, pblk);
ext4_es_store_status(&newes, status);
trace_ext4_es_insert_extent(inode, &newes);
ext4_es_insert_extent_check(inode, &newes);
write_lock(&EXT4_I(inode)->i_es_lock);
err = __es_remove_extent(inode, lblk, end);
if (err != 0)
goto error;
err = __es_insert_extent(inode, &newes);
error:
write_unlock(&EXT4_I(inode)->i_es_lock);
ext4_es_print_tree(inode);
return err;
}
/*
* ext4_es_lookup_extent() looks up an extent in extent status tree.
*
* ext4_es_lookup_extent is called by ext4_map_blocks/ext4_da_map_blocks.
*
* Return: 1 on found, 0 on not
*/
int ext4_es_lookup_extent(struct inode *inode, ext4_lblk_t lblk,
struct extent_status *es)
{
struct ext4_es_tree *tree;
struct extent_status *es1 = NULL;
struct rb_node *node;
int found = 0;
trace_ext4_es_lookup_extent_enter(inode, lblk);
es_debug("lookup extent in block %u\n", lblk);
tree = &EXT4_I(inode)->i_es_tree;
read_lock(&EXT4_I(inode)->i_es_lock);
/* find extent in cache firstly */
es->es_lblk = es->es_len = es->es_pblk = 0;
if (tree->cache_es) {
es1 = tree->cache_es;
if (in_range(lblk, es1->es_lblk, es1->es_len)) {
es_debug("%u cached by [%u/%u)\n",
lblk, es1->es_lblk, es1->es_len);
found = 1;
goto out;
}
}
node = tree->root.rb_node;
while (node) {
es1 = rb_entry(node, struct extent_status, rb_node);
if (lblk < es1->es_lblk)
node = node->rb_left;
else if (lblk > ext4_es_end(es1))
node = node->rb_right;
else {
found = 1;
break;
}
}
out:
if (found) {
BUG_ON(!es1);
es->es_lblk = es1->es_lblk;
es->es_len = es1->es_len;
es->es_pblk = es1->es_pblk;
}
read_unlock(&EXT4_I(inode)->i_es_lock);
trace_ext4_es_lookup_extent_exit(inode, es, found);
return found;
}
static int __es_remove_extent(struct inode *inode, ext4_lblk_t lblk,
ext4_lblk_t end)
{
struct ext4_es_tree *tree = &EXT4_I(inode)->i_es_tree;
struct rb_node *node;
struct extent_status *es;
struct extent_status orig_es;
ext4_lblk_t len1, len2;
ext4_fsblk_t block;
int err = 0;
es = __es_tree_search(&tree->root, lblk);
if (!es)
goto out;
if (es->es_lblk > end)
goto out;
/* Simply invalidate cache_es. */
tree->cache_es = NULL;
orig_es.es_lblk = es->es_lblk;
orig_es.es_len = es->es_len;
orig_es.es_pblk = es->es_pblk;
len1 = lblk > es->es_lblk ? lblk - es->es_lblk : 0;
len2 = ext4_es_end(es) > end ? ext4_es_end(es) - end : 0;
if (len1 > 0)
es->es_len = len1;
if (len2 > 0) {
if (len1 > 0) {
struct extent_status newes;
newes.es_lblk = end + 1;
newes.es_len = len2;
if (ext4_es_is_written(&orig_es) ||
ext4_es_is_unwritten(&orig_es)) {
block = ext4_es_pblock(&orig_es) +
orig_es.es_len - len2;
ext4_es_store_pblock(&newes, block);
}
ext4_es_store_status(&newes, ext4_es_status(&orig_es));
err = __es_insert_extent(inode, &newes);
if (err) {
es->es_lblk = orig_es.es_lblk;
es->es_len = orig_es.es_len;
goto out;
}
} else {
es->es_lblk = end + 1;
es->es_len = len2;
if (ext4_es_is_written(es) ||
ext4_es_is_unwritten(es)) {
block = orig_es.es_pblk + orig_es.es_len - len2;
ext4_es_store_pblock(es, block);
}
}
goto out;
}
if (len1 > 0) {
node = rb_next(&es->rb_node);
if (node)
es = rb_entry(node, struct extent_status, rb_node);
else
es = NULL;
}
while (es && ext4_es_end(es) <= end) {
node = rb_next(&es->rb_node);
rb_erase(&es->rb_node, &tree->root);
ext4_es_free_extent(inode, es);
if (!node) {
es = NULL;
break;
}
es = rb_entry(node, struct extent_status, rb_node);
}
if (es && es->es_lblk < end + 1) {
ext4_lblk_t orig_len = es->es_len;
len1 = ext4_es_end(es) - end;
es->es_lblk = end + 1;
es->es_len = len1;
if (ext4_es_is_written(es) || ext4_es_is_unwritten(es)) {
block = es->es_pblk + orig_len - len1;
ext4_es_store_pblock(es, block);
}
}
out:
return err;
}
/*
* ext4_es_remove_extent() removes a space from a extent status tree.
*
* Return 0 on success, error code on failure.
*/
int ext4_es_remove_extent(struct inode *inode, ext4_lblk_t lblk,
ext4_lblk_t len)
{
ext4_lblk_t end;
int err = 0;
trace_ext4_es_remove_extent(inode, lblk, len);
es_debug("remove [%u/%u) from extent status tree of inode %lu\n",
lblk, len, inode->i_ino);
if (!len)
return err;
end = lblk + len - 1;
BUG_ON(end < lblk);
write_lock(&EXT4_I(inode)->i_es_lock);
err = __es_remove_extent(inode, lblk, end);
write_unlock(&EXT4_I(inode)->i_es_lock);
ext4_es_print_tree(inode);
return err;
}
int ext4_es_zeroout(struct inode *inode, struct ext4_extent *ex)
{
ext4_lblk_t ee_block;
ext4_fsblk_t ee_pblock;
unsigned int ee_len;
ee_block = le32_to_cpu(ex->ee_block);
ee_len = ext4_ext_get_actual_len(ex);
ee_pblock = ext4_ext_pblock(ex);
if (ee_len == 0)
return 0;
return ext4_es_insert_extent(inode, ee_block, ee_len, ee_pblock,
EXTENT_STATUS_WRITTEN);
}
static int ext4_inode_touch_time_cmp(void *priv, struct list_head *a,
struct list_head *b)
{
struct ext4_inode_info *eia, *eib;
eia = list_entry(a, struct ext4_inode_info, i_es_lru);
eib = list_entry(b, struct ext4_inode_info, i_es_lru);
if (eia->i_touch_when == eib->i_touch_when)
return 0;
if (time_after(eia->i_touch_when, eib->i_touch_when))
return 1;
else
return -1;
}
static int ext4_es_shrink(struct shrinker *shrink, struct shrink_control *sc)
{
struct ext4_sb_info *sbi = container_of(shrink,
struct ext4_sb_info, s_es_shrinker);
struct ext4_inode_info *ei;
struct list_head *cur, *tmp;
LIST_HEAD(skiped);
int nr_to_scan = sc->nr_to_scan;
int ret, nr_shrunk = 0;
ret = percpu_counter_read_positive(&sbi->s_extent_cache_cnt);
trace_ext4_es_shrink_enter(sbi->s_sb, nr_to_scan, ret);
if (!nr_to_scan)
return ret;
spin_lock(&sbi->s_es_lru_lock);
/*
* If the inode that is at the head of LRU list is newer than
* last_sorted time, that means that we need to sort this list.
*/
ei = list_first_entry(&sbi->s_es_lru, struct ext4_inode_info, i_es_lru);
if (sbi->s_es_last_sorted < ei->i_touch_when) {
list_sort(NULL, &sbi->s_es_lru, ext4_inode_touch_time_cmp);
sbi->s_es_last_sorted = jiffies;
}
list_for_each_safe(cur, tmp, &sbi->s_es_lru) {
/*
* If we have already reclaimed all extents from extent
* status tree, just stop the loop immediately.
*/
if (percpu_counter_read_positive(&sbi->s_extent_cache_cnt) == 0)
break;
ei = list_entry(cur, struct ext4_inode_info, i_es_lru);
/* Skip the inode that is newer than the last_sorted time */
if (sbi->s_es_last_sorted < ei->i_touch_when) {
list_move_tail(cur, &skiped);
continue;
}
if (ei->i_es_lru_nr == 0)
continue;
write_lock(&ei->i_es_lock);
ret = __es_try_to_reclaim_extents(ei, nr_to_scan);
if (ei->i_es_lru_nr == 0)
list_del_init(&ei->i_es_lru);
write_unlock(&ei->i_es_lock);
nr_shrunk += ret;
nr_to_scan -= ret;
if (nr_to_scan == 0)
break;
}
/* Move the newer inodes into the tail of the LRU list. */
list_splice_tail(&skiped, &sbi->s_es_lru);
spin_unlock(&sbi->s_es_lru_lock);
ret = percpu_counter_read_positive(&sbi->s_extent_cache_cnt);
trace_ext4_es_shrink_exit(sbi->s_sb, nr_shrunk, ret);
return ret;
}
void ext4_es_register_shrinker(struct ext4_sb_info *sbi)
{
INIT_LIST_HEAD(&sbi->s_es_lru);
spin_lock_init(&sbi->s_es_lru_lock);
sbi->s_es_last_sorted = 0;
sbi->s_es_shrinker.shrink = ext4_es_shrink;
sbi->s_es_shrinker.seeks = DEFAULT_SEEKS;
register_shrinker(&sbi->s_es_shrinker);
}
void ext4_es_unregister_shrinker(struct ext4_sb_info *sbi)
{
unregister_shrinker(&sbi->s_es_shrinker);
}
void ext4_es_lru_add(struct inode *inode)
{
struct ext4_inode_info *ei = EXT4_I(inode);
struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
ei->i_touch_when = jiffies;
if (!list_empty(&ei->i_es_lru))
return;
spin_lock(&sbi->s_es_lru_lock);
if (list_empty(&ei->i_es_lru))
list_add_tail(&ei->i_es_lru, &sbi->s_es_lru);
spin_unlock(&sbi->s_es_lru_lock);
}
void ext4_es_lru_del(struct inode *inode)
{
struct ext4_inode_info *ei = EXT4_I(inode);
struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
spin_lock(&sbi->s_es_lru_lock);
if (!list_empty(&ei->i_es_lru))
list_del_init(&ei->i_es_lru);
spin_unlock(&sbi->s_es_lru_lock);
}
static int __es_try_to_reclaim_extents(struct ext4_inode_info *ei,
int nr_to_scan)
{
struct inode *inode = &ei->vfs_inode;
struct ext4_es_tree *tree = &ei->i_es_tree;
struct rb_node *node;
struct extent_status *es;
int nr_shrunk = 0;
if (ei->i_es_lru_nr == 0)
return 0;
node = rb_first(&tree->root);
while (node != NULL) {
es = rb_entry(node, struct extent_status, rb_node);
node = rb_next(&es->rb_node);
/*
* We can't reclaim delayed extent from status tree because
* fiemap, bigallic, and seek_data/hole need to use it.
*/
if (!ext4_es_is_delayed(es)) {
rb_erase(&es->rb_node, &tree->root);
ext4_es_free_extent(inode, es);
nr_shrunk++;
if (--nr_to_scan == 0)
break;
}
}
tree->cache_es = NULL;
return nr_shrunk;
}
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