Google Git
Sign in
android-kvm / linux / 72641d8d60401a5f1e1a0431ceaf928680d34418 / . / fs / ext4 / mballoc.c
blob: 215b7068f548a67d96f11979393d4394f2d6fc1e [file] [log] [blame]
// SPDX-License-Identifier: GPL-2.0
/*
* Copyright (c) 2003-2006, Cluster File Systems, Inc, info@clusterfs.com
* Written by Alex Tomas <alex@clusterfs.com>
*/
/*
* mballoc.c contains the multiblocks allocation routines
*/
#include "ext4_jbd2.h"
#include "mballoc.h"
#include <linux/log2.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/nospec.h>
#include <linux/backing-dev.h>
#include <trace/events/ext4.h>
/*
* MUSTDO:
* - test ext4_ext_search_left() and ext4_ext_search_right()
* - search for metadata in few groups
*
* TODO v4:
* - normalization should take into account whether file is still open
* - discard preallocations if no free space left (policy?)
* - don't normalize tails
* - quota
* - reservation for superuser
*
* TODO v3:
* - bitmap read-ahead (proposed by Oleg Drokin aka green)
* - track min/max extents in each group for better group selection
* - mb_mark_used() may allocate chunk right after splitting buddy
* - tree of groups sorted by number of free blocks
* - error handling
*/
/*
* The allocation request involve request for multiple number of blocks
* near to the goal(block) value specified.
*
* During initialization phase of the allocator we decide to use the
* group preallocation or inode preallocation depending on the size of
* the file. The size of the file could be the resulting file size we
* would have after allocation, or the current file size, which ever
* is larger. If the size is less than sbi->s_mb_stream_request we
* select to use the group preallocation. The default value of
* s_mb_stream_request is 16 blocks. This can also be tuned via
* /sys/fs/ext4/<partition>/mb_stream_req. The value is represented in
* terms of number of blocks.
*
* The main motivation for having small file use group preallocation is to
* ensure that we have small files closer together on the disk.
*
* First stage the allocator looks at the inode prealloc list,
* ext4_inode_info->i_prealloc_list, which contains list of prealloc
* spaces for this particular inode. The inode prealloc space is
* represented as:
*
* pa_lstart -> the logical start block for this prealloc space
* pa_pstart -> the physical start block for this prealloc space
* pa_len -> length for this prealloc space (in clusters)
* pa_free -> free space available in this prealloc space (in clusters)
*
* The inode preallocation space is used looking at the _logical_ start
* block. If only the logical file block falls within the range of prealloc
* space we will consume the particular prealloc space. This makes sure that
* we have contiguous physical blocks representing the file blocks
*
* The important thing to be noted in case of inode prealloc space is that
* we don't modify the values associated to inode prealloc space except
* pa_free.
*
* If we are not able to find blocks in the inode prealloc space and if we
* have the group allocation flag set then we look at the locality group
* prealloc space. These are per CPU prealloc list represented as
*
* ext4_sb_info.s_locality_groups[smp_processor_id()]
*
* The reason for having a per cpu locality group is to reduce the contention
* between CPUs. It is possible to get scheduled at this point.
*
* The locality group prealloc space is used looking at whether we have
* enough free space (pa_free) within the prealloc space.
*
* If we can't allocate blocks via inode prealloc or/and locality group
* prealloc then we look at the buddy cache. The buddy cache is represented
* by ext4_sb_info.s_buddy_cache (struct inode) whose file offset gets
* mapped to the buddy and bitmap information regarding different
* groups. The buddy information is attached to buddy cache inode so that
* we can access them through the page cache. The information regarding
* each group is loaded via ext4_mb_load_buddy. The information involve
* block bitmap and buddy information. The information are stored in the
* inode as:
*
* { page }
* [ group 0 bitmap][ group 0 buddy] [group 1][ group 1]...
*
*
* one block each for bitmap and buddy information. So for each group we
* take up 2 blocks. A page can contain blocks_per_page (PAGE_SIZE /
* blocksize) blocks. So it can have information regarding groups_per_page
* which is blocks_per_page/2
*
* The buddy cache inode is not stored on disk. The inode is thrown
* away when the filesystem is unmounted.
*
* We look for count number of blocks in the buddy cache. If we were able
* to locate that many free blocks we return with additional information
* regarding rest of the contiguous physical block available
*
* Before allocating blocks via buddy cache we normalize the request
* blocks. This ensure we ask for more blocks that we needed. The extra
* blocks that we get after allocation is added to the respective prealloc
* list. In case of inode preallocation we follow a list of heuristics
* based on file size. This can be found in ext4_mb_normalize_request. If
* we are doing a group prealloc we try to normalize the request to
* sbi->s_mb_group_prealloc. The default value of s_mb_group_prealloc is
* dependent on the cluster size; for non-bigalloc file systems, it is
* 512 blocks. This can be tuned via
* /sys/fs/ext4/<partition>/mb_group_prealloc. The value is represented in
* terms of number of blocks. If we have mounted the file system with -O
* stripe=<value> option the group prealloc request is normalized to the
* smallest multiple of the stripe value (sbi->s_stripe) which is
* greater than the default mb_group_prealloc.
*
* If "mb_optimize_scan" mount option is set, we maintain in memory group info
* structures in two data structures:
*
* 1) Array of largest free order lists (sbi->s_mb_largest_free_orders)
*
* Locking: sbi->s_mb_largest_free_orders_locks(array of rw locks)
*
* This is an array of lists where the index in the array represents the
* largest free order in the buddy bitmap of the participating group infos of
* that list. So, there are exactly MB_NUM_ORDERS(sb) (which means total
* number of buddy bitmap orders possible) number of lists. Group-infos are
* placed in appropriate lists.
*
* 2) Average fragment size rb tree (sbi->s_mb_avg_fragment_size_root)
*
* Locking: sbi->s_mb_rb_lock (rwlock)
*
* This is a red black tree consisting of group infos and the tree is sorted
* by average fragment sizes (which is calculated as ext4_group_info->bb_free
* / ext4_group_info->bb_fragments).
*
* When "mb_optimize_scan" mount option is set, mballoc consults the above data
* structures to decide the order in which groups are to be traversed for
* fulfilling an allocation request.
*
* At CR = 0, we look for groups which have the largest_free_order >= the order
* of the request. We directly look at the largest free order list in the data
* structure (1) above where largest_free_order = order of the request. If that
* list is empty, we look at remaining list in the increasing order of
* largest_free_order. This allows us to perform CR = 0 lookup in O(1) time.
*
* At CR = 1, we only consider groups where average fragment size > request
* size. So, we lookup a group which has average fragment size just above or
* equal to request size using our rb tree (data structure 2) in O(log N) time.
*
* If "mb_optimize_scan" mount option is not set, mballoc traverses groups in
* linear order which requires O(N) search time for each CR 0 and CR 1 phase.
*
* The regular allocator (using the buddy cache) supports a few tunables.
*
* /sys/fs/ext4/<partition>/mb_min_to_scan
* /sys/fs/ext4/<partition>/mb_max_to_scan
* /sys/fs/ext4/<partition>/mb_order2_req
* /sys/fs/ext4/<partition>/mb_linear_limit
*
* The regular allocator uses buddy scan only if the request len is power of
* 2 blocks and the order of allocation is >= sbi->s_mb_order2_reqs. The
* value of s_mb_order2_reqs can be tuned via
* /sys/fs/ext4/<partition>/mb_order2_req. If the request len is equal to
* stripe size (sbi->s_stripe), we try to search for contiguous block in
* stripe size. This should result in better allocation on RAID setups. If
* not, we search in the specific group using bitmap for best extents. The
* tunable min_to_scan and max_to_scan control the behaviour here.
* min_to_scan indicate how long the mballoc __must__ look for a best
* extent and max_to_scan indicates how long the mballoc __can__ look for a
* best extent in the found extents. Searching for the blocks starts with
* the group specified as the goal value in allocation context via
* ac_g_ex. Each group is first checked based on the criteria whether it
* can be used for allocation. ext4_mb_good_group explains how the groups are
* checked.
*
* When "mb_optimize_scan" is turned on, as mentioned above, the groups may not
* get traversed linearly. That may result in subsequent allocations being not
* close to each other. And so, the underlying device may get filled up in a
* non-linear fashion. While that may not matter on non-rotational devices, for
* rotational devices that may result in higher seek times. "mb_linear_limit"
* tells mballoc how many groups mballoc should search linearly before
* performing consulting above data structures for more efficient lookups. For
* non rotational devices, this value defaults to 0 and for rotational devices
* this is set to MB_DEFAULT_LINEAR_LIMIT.
*
* Both the prealloc space are getting populated as above. So for the first
* request we will hit the buddy cache which will result in this prealloc
* space getting filled. The prealloc space is then later used for the
* subsequent request.
*/
/*
* mballoc operates on the following data:
* - on-disk bitmap
* - in-core buddy (actually includes buddy and bitmap)
* - preallocation descriptors (PAs)
*
* there are two types of preallocations:
* - inode
* assiged to specific inode and can be used for this inode only.
* it describes part of inode's space preallocated to specific
* physical blocks. any block from that preallocated can be used
* independent. the descriptor just tracks number of blocks left
* unused. so, before taking some block from descriptor, one must
* make sure corresponded logical block isn't allocated yet. this
* also means that freeing any block within descriptor's range
* must discard all preallocated blocks.
* - locality group
* assigned to specific locality group which does not translate to
* permanent set of inodes: inode can join and leave group. space
* from this type of preallocation can be used for any inode. thus
* it's consumed from the beginning to the end.
*
* relation between them can be expressed as:
* in-core buddy = on-disk bitmap + preallocation descriptors
*
* this mean blocks mballoc considers used are:
* - allocated blocks (persistent)
* - preallocated blocks (non-persistent)
*
* consistency in mballoc world means that at any time a block is either
* free or used in ALL structures. notice: "any time" should not be read
* literally -- time is discrete and delimited by locks.
*
* to keep it simple, we don't use block numbers, instead we count number of
* blocks: how many blocks marked used/free in on-disk bitmap, buddy and PA.
*
* all operations can be expressed as:
* - init buddy: buddy = on-disk + PAs
* - new PA: buddy += N; PA = N
* - use inode PA: on-disk += N; PA -= N
* - discard inode PA buddy -= on-disk - PA; PA = 0
* - use locality group PA on-disk += N; PA -= N
* - discard locality group PA buddy -= PA; PA = 0
* note: 'buddy -= on-disk - PA' is used to show that on-disk bitmap
* is used in real operation because we can't know actual used
* bits from PA, only from on-disk bitmap
*
* if we follow this strict logic, then all operations above should be atomic.
* given some of them can block, we'd have to use something like semaphores
* killing performance on high-end SMP hardware. let's try to relax it using
* the following knowledge:
* 1) if buddy is referenced, it's already initialized
* 2) while block is used in buddy and the buddy is referenced,
* nobody can re-allocate that block
* 3) we work on bitmaps and '+' actually means 'set bits'. if on-disk has
* bit set and PA claims same block, it's OK. IOW, one can set bit in
* on-disk bitmap if buddy has same bit set or/and PA covers corresponded
* block
*
* so, now we're building a concurrency table:
* - init buddy vs.
* - new PA
* blocks for PA are allocated in the buddy, buddy must be referenced
* until PA is linked to allocation group to avoid concurrent buddy init
* - use inode PA
* we need to make sure that either on-disk bitmap or PA has uptodate data
* given (3) we care that PA-=N operation doesn't interfere with init
* - discard inode PA
* the simplest way would be to have buddy initialized by the discard
* - use locality group PA
* again PA-=N must be serialized with init
* - discard locality group PA
* the simplest way would be to have buddy initialized by the discard
* - new PA vs.
* - use inode PA
* i_data_sem serializes them
* - discard inode PA
* discard process must wait until PA isn't used by another process
* - use locality group PA
* some mutex should serialize them
* - discard locality group PA
* discard process must wait until PA isn't used by another process
* - use inode PA
* - use inode PA
* i_data_sem or another mutex should serializes them
* - discard inode PA
* discard process must wait until PA isn't used by another process
* - use locality group PA
* nothing wrong here -- they're different PAs covering different blocks
* - discard locality group PA
* discard process must wait until PA isn't used by another process
*
* now we're ready to make few consequences:
* - PA is referenced and while it is no discard is possible
* - PA is referenced until block isn't marked in on-disk bitmap
* - PA changes only after on-disk bitmap
* - discard must not compete with init. either init is done before
* any discard or they're serialized somehow
* - buddy init as sum of on-disk bitmap and PAs is done atomically
*
* a special case when we've used PA to emptiness. no need to modify buddy
* in this case, but we should care about concurrent init
*
*/
/*
* Logic in few words:
*
* - allocation:
* load group
* find blocks
* mark bits in on-disk bitmap
* release group
*
* - use preallocation:
* find proper PA (per-inode or group)
* load group
* mark bits in on-disk bitmap
* release group
* release PA
*
* - free:
* load group
* mark bits in on-disk bitmap
* release group
*
* - discard preallocations in group:
* mark PAs deleted
* move them onto local list
* load on-disk bitmap
* load group
* remove PA from object (inode or locality group)
* mark free blocks in-core
*
* - discard inode's preallocations:
*/
/*
* Locking rules
*
* Locks:
* - bitlock on a group (group)
* - object (inode/locality) (object)
* - per-pa lock (pa)
* - cr0 lists lock (cr0)
* - cr1 tree lock (cr1)
*
* Paths:
* - new pa
* object
* group
*
* - find and use pa:
* pa
*
* - release consumed pa:
* pa
* group
* object
*
* - generate in-core bitmap:
* group
* pa
*
* - discard all for given object (inode, locality group):
* object
* pa
* group
*
* - discard all for given group:
* group
* pa
* group
* object
*
* - allocation path (ext4_mb_regular_allocator)
* group
* cr0/cr1
*/
static struct kmem_cache *ext4_pspace_cachep;
static struct kmem_cache *ext4_ac_cachep;
static struct kmem_cache *ext4_free_data_cachep;
/* We create slab caches for groupinfo data structures based on the
* superblock block size. There will be one per mounted filesystem for
* each unique s_blocksize_bits */
#define NR_GRPINFO_CACHES 8
static struct kmem_cache *ext4_groupinfo_caches[NR_GRPINFO_CACHES];
static const char * const ext4_groupinfo_slab_names[NR_GRPINFO_CACHES] = {
"ext4_groupinfo_1k", "ext4_groupinfo_2k", "ext4_groupinfo_4k",
"ext4_groupinfo_8k", "ext4_groupinfo_16k", "ext4_groupinfo_32k",
"ext4_groupinfo_64k", "ext4_groupinfo_128k"
};
static void ext4_mb_generate_from_pa(struct super_block *sb, void *bitmap,
ext4_group_t group);
static void ext4_mb_generate_from_freelist(struct super_block *sb, void *bitmap,
ext4_group_t group);
static void ext4_mb_new_preallocation(struct ext4_allocation_context *ac);
static bool ext4_mb_good_group(struct ext4_allocation_context *ac,
ext4_group_t group, int cr);
static int ext4_try_to_trim_range(struct super_block *sb,
struct ext4_buddy *e4b, ext4_grpblk_t start,
ext4_grpblk_t max, ext4_grpblk_t minblocks);
/*
* The algorithm using this percpu seq counter goes below:
* 1. We sample the percpu discard_pa_seq counter before trying for block
* allocation in ext4_mb_new_blocks().
* 2. We increment this percpu discard_pa_seq counter when we either allocate
* or free these blocks i.e. while marking those blocks as used/free in
* mb_mark_used()/mb_free_blocks().
* 3. We also increment this percpu seq counter when we successfully identify
* that the bb_prealloc_list is not empty and hence proceed for discarding
* of those PAs inside ext4_mb_discard_group_preallocations().
*
* Now to make sure that the regular fast path of block allocation is not
* affected, as a small optimization we only sample the percpu seq counter
* on that cpu. Only when the block allocation fails and when freed blocks
* found were 0, that is when we sample percpu seq counter for all cpus using
* below function ext4_get_discard_pa_seq_sum(). This happens after making
* sure that all the PAs on grp->bb_prealloc_list got freed or if it's empty.
*/
static DEFINE_PER_CPU(u64, discard_pa_seq);
static inline u64 ext4_get_discard_pa_seq_sum(void)
{
int __cpu;
u64 __seq = 0;
for_each_possible_cpu(__cpu)
__seq += per_cpu(discard_pa_seq, __cpu);
return __seq;
}
static inline void *mb_correct_addr_and_bit(int *bit, void *addr)
{
#if BITS_PER_LONG == 64
*bit += ((unsigned long) addr & 7UL) << 3;
addr = (void *) ((unsigned long) addr & ~7UL);
#elif BITS_PER_LONG == 32
*bit += ((unsigned long) addr & 3UL) << 3;
addr = (void *) ((unsigned long) addr & ~3UL);
#else
#error "how many bits you are?!"
#endif
return addr;
}
static inline int mb_test_bit(int bit, void *addr)
{
/*
* ext4_test_bit on architecture like powerpc
* needs unsigned long aligned address
*/
addr = mb_correct_addr_and_bit(&bit, addr);
return ext4_test_bit(bit, addr);
}
static inline void mb_set_bit(int bit, void *addr)
{
addr = mb_correct_addr_and_bit(&bit, addr);
ext4_set_bit(bit, addr);
}
static inline void mb_clear_bit(int bit, void *addr)
{
addr = mb_correct_addr_and_bit(&bit, addr);
ext4_clear_bit(bit, addr);
}
static inline int mb_test_and_clear_bit(int bit, void *addr)
{
addr = mb_correct_addr_and_bit(&bit, addr);
return ext4_test_and_clear_bit(bit, addr);
}
static inline int mb_find_next_zero_bit(void *addr, int max, int start)
{
int fix = 0, ret, tmpmax;
addr = mb_correct_addr_and_bit(&fix, addr);
tmpmax = max + fix;
start += fix;
ret = ext4_find_next_zero_bit(addr, tmpmax, start) - fix;
if (ret > max)
return max;
return ret;
}
static inline int mb_find_next_bit(void *addr, int max, int start)
{
int fix = 0, ret, tmpmax;
addr = mb_correct_addr_and_bit(&fix, addr);
tmpmax = max + fix;
start += fix;
ret = ext4_find_next_bit(addr, tmpmax, start) - fix;
if (ret > max)
return max;
return ret;
}
static void *mb_find_buddy(struct ext4_buddy *e4b, int order, int *max)
{
char *bb;
BUG_ON(e4b->bd_bitmap == e4b->bd_buddy);
BUG_ON(max == NULL);
if (order > e4b->bd_blkbits + 1) {
*max = 0;
return NULL;
}
/* at order 0 we see each particular block */
if (order == 0) {
*max = 1 << (e4b->bd_blkbits + 3);
return e4b->bd_bitmap;
}
bb = e4b->bd_buddy + EXT4_SB(e4b->bd_sb)->s_mb_offsets[order];
*max = EXT4_SB(e4b->bd_sb)->s_mb_maxs[order];
return bb;
}
#ifdef DOUBLE_CHECK
static void mb_free_blocks_double(struct inode *inode, struct ext4_buddy *e4b,
int first, int count)
{
int i;
struct super_block *sb = e4b->bd_sb;
if (unlikely(e4b->bd_info->bb_bitmap == NULL))
return;
assert_spin_locked(ext4_group_lock_ptr(sb, e4b->bd_group));
for (i = 0; i < count; i++) {
if (!mb_test_bit(first + i, e4b->bd_info->bb_bitmap)) {
ext4_fsblk_t blocknr;
blocknr = ext4_group_first_block_no(sb, e4b->bd_group);
blocknr += EXT4_C2B(EXT4_SB(sb), first + i);
ext4_grp_locked_error(sb, e4b->bd_group,
inode ? inode->i_ino : 0,
blocknr,
"freeing block already freed "
"(bit %u)",
first + i);
ext4_mark_group_bitmap_corrupted(sb, e4b->bd_group,
EXT4_GROUP_INFO_BBITMAP_CORRUPT);
}
mb_clear_bit(first + i, e4b->bd_info->bb_bitmap);
}
}
static void mb_mark_used_double(struct ext4_buddy *e4b, int first, int count)
{
int i;
if (unlikely(e4b->bd_info->bb_bitmap == NULL))
return;
assert_spin_locked(ext4_group_lock_ptr(e4b->bd_sb, e4b->bd_group));
for (i = 0; i < count; i++) {
BUG_ON(mb_test_bit(first + i, e4b->bd_info->bb_bitmap));
mb_set_bit(first + i, e4b->bd_info->bb_bitmap);
}
}
static void mb_cmp_bitmaps(struct ext4_buddy *e4b, void *bitmap)
{
if (unlikely(e4b->bd_info->bb_bitmap == NULL))
return;
if (memcmp(e4b->bd_info->bb_bitmap, bitmap, e4b->bd_sb->s_blocksize)) {
unsigned char *b1, *b2;
int i;
b1 = (unsigned char *) e4b->bd_info->bb_bitmap;
b2 = (unsigned char *) bitmap;
for (i = 0; i < e4b->bd_sb->s_blocksize; i++) {
if (b1[i] != b2[i]) {
ext4_msg(e4b->bd_sb, KERN_ERR,
"corruption in group %u "
"at byte %u(%u): %x in copy != %x "
"on disk/prealloc",
e4b->bd_group, i, i * 8, b1[i], b2[i]);
BUG();
}
}
}
}
static void mb_group_bb_bitmap_alloc(struct super_block *sb,
struct ext4_group_info *grp, ext4_group_t group)
{
struct buffer_head *bh;
grp->bb_bitmap = kmalloc(sb->s_blocksize, GFP_NOFS);
if (!grp->bb_bitmap)
return;
bh = ext4_read_block_bitmap(sb, group);
if (IS_ERR_OR_NULL(bh)) {
kfree(grp->bb_bitmap);
grp->bb_bitmap = NULL;
return;
}
memcpy(grp->bb_bitmap, bh->b_data, sb->s_blocksize);
put_bh(bh);
}
static void mb_group_bb_bitmap_free(struct ext4_group_info *grp)
{
kfree(grp->bb_bitmap);
}
#else
static inline void mb_free_blocks_double(struct inode *inode,
struct ext4_buddy *e4b, int first, int count)
{
return;
}
static inline void mb_mark_used_double(struct ext4_buddy *e4b,
int first, int count)
{
return;
}
static inline void mb_cmp_bitmaps(struct ext4_buddy *e4b, void *bitmap)
{
return;
}
static inline void mb_group_bb_bitmap_alloc(struct super_block *sb,
struct ext4_group_info *grp, ext4_group_t group)
{
return;
}
static inline void mb_group_bb_bitmap_free(struct ext4_group_info *grp)
{
return;
}
#endif
#ifdef AGGRESSIVE_CHECK
#define MB_CHECK_ASSERT(assert) \
do { \
if (!(assert)) { \
printk(KERN_EMERG \
"Assertion failure in %s() at %s:%d: \"%s\"\n", \
function, file, line, # assert); \
BUG(); \
} \
} while (0)
static int __mb_check_buddy(struct ext4_buddy *e4b, char *file,
const char *function, int line)
{
struct super_block *sb = e4b->bd_sb;
int order = e4b->bd_blkbits + 1;
int max;
int max2;
int i;
int j;
int k;
int count;
struct ext4_group_info *grp;
int fragments = 0;
int fstart;
struct list_head *cur;
void *buddy;
void *buddy2;
if (e4b->bd_info->bb_check_counter++ % 10)
return 0;
while (order > 1) {
buddy = mb_find_buddy(e4b, order, &max);
MB_CHECK_ASSERT(buddy);
buddy2 = mb_find_buddy(e4b, order - 1, &max2);
MB_CHECK_ASSERT(buddy2);
MB_CHECK_ASSERT(buddy != buddy2);
MB_CHECK_ASSERT(max * 2 == max2);
count = 0;
for (i = 0; i < max; i++) {
if (mb_test_bit(i, buddy)) {
/* only single bit in buddy2 may be 1 */
if (!mb_test_bit(i << 1, buddy2)) {
MB_CHECK_ASSERT(
mb_test_bit((i<<1)+1, buddy2));
} else if (!mb_test_bit((i << 1) + 1, buddy2)) {
MB_CHECK_ASSERT(
mb_test_bit(i << 1, buddy2));
}
continue;
}
/* both bits in buddy2 must be 1 */
MB_CHECK_ASSERT(mb_test_bit(i << 1, buddy2));
MB_CHECK_ASSERT(mb_test_bit((i << 1) + 1, buddy2));
for (j = 0; j < (1 << order); j++) {
k = (i * (1 << order)) + j;
MB_CHECK_ASSERT(
!mb_test_bit(k, e4b->bd_bitmap));
}
count++;
}
MB_CHECK_ASSERT(e4b->bd_info->bb_counters[order] == count);
order--;
}
fstart = -1;
buddy = mb_find_buddy(e4b, 0, &max);
for (i = 0; i < max; i++) {
if (!mb_test_bit(i, buddy)) {
MB_CHECK_ASSERT(i >= e4b->bd_info->bb_first_free);
if (fstart == -1) {
fragments++;
fstart = i;
}
continue;
}
fstart = -1;
/* check used bits only */
for (j = 0; j < e4b->bd_blkbits + 1; j++) {
buddy2 = mb_find_buddy(e4b, j, &max2);
k = i >> j;
MB_CHECK_ASSERT(k < max2);
MB_CHECK_ASSERT(mb_test_bit(k, buddy2));
}
}
MB_CHECK_ASSERT(!EXT4_MB_GRP_NEED_INIT(e4b->bd_info));
MB_CHECK_ASSERT(e4b->bd_info->bb_fragments == fragments);
grp = ext4_get_group_info(sb, e4b->bd_group);
list_for_each(cur, &grp->bb_prealloc_list) {
ext4_group_t groupnr;
struct ext4_prealloc_space *pa;
pa = list_entry(cur, struct ext4_prealloc_space, pa_group_list);
ext4_get_group_no_and_offset(sb, pa->pa_pstart, &groupnr, &k);
MB_CHECK_ASSERT(groupnr == e4b->bd_group);
for (i = 0; i < pa->pa_len; i++)
MB_CHECK_ASSERT(mb_test_bit(k + i, buddy));
}
return 0;
}
#undef MB_CHECK_ASSERT
#define mb_check_buddy(e4b) __mb_check_buddy(e4b, \
__FILE__, __func__, __LINE__)
#else
#define mb_check_buddy(e4b)
#endif
/*
* Divide blocks started from @first with length @len into
* smaller chunks with power of 2 blocks.
* Clear the bits in bitmap which the blocks of the chunk(s) covered,
* then increase bb_counters[] for corresponded chunk size.
*/
static void ext4_mb_mark_free_simple(struct super_block *sb,
void *buddy, ext4_grpblk_t first, ext4_grpblk_t len,
struct ext4_group_info *grp)
{
struct ext4_sb_info *sbi = EXT4_SB(sb);
ext4_grpblk_t min;
ext4_grpblk_t max;
ext4_grpblk_t chunk;
unsigned int border;
BUG_ON(len > EXT4_CLUSTERS_PER_GROUP(sb));
border = 2 << sb->s_blocksize_bits;
while (len > 0) {
/* find how many blocks can be covered since this position */
max = ffs(first | border) - 1;
/* find how many blocks of power 2 we need to mark */
min = fls(len) - 1;
if (max < min)
min = max;
chunk = 1 << min;
/* mark multiblock chunks only */
grp->bb_counters[min]++;
if (min > 0)
mb_clear_bit(first >> min,
buddy + sbi->s_mb_offsets[min]);
len -= chunk;
first += chunk;
}
}
static void ext4_mb_rb_insert(struct rb_root *root, struct rb_node *new,
int (*cmp)(struct rb_node *, struct rb_node *))
{
struct rb_node **iter = &root->rb_node, *parent = NULL;
while (*iter) {
parent = *iter;
if (cmp(new, *iter) > 0)
iter = &((*iter)->rb_left);
else
iter = &((*iter)->rb_right);
}
rb_link_node(new, parent, iter);
rb_insert_color(new, root);
}
static int
ext4_mb_avg_fragment_size_cmp(struct rb_node *rb1, struct rb_node *rb2)
{
struct ext4_group_info *grp1 = rb_entry(rb1,
struct ext4_group_info,
bb_avg_fragment_size_rb);
struct ext4_group_info *grp2 = rb_entry(rb2,
struct ext4_group_info,
bb_avg_fragment_size_rb);
int num_frags_1, num_frags_2;
num_frags_1 = grp1->bb_fragments ?
grp1->bb_free / grp1->bb_fragments : 0;
num_frags_2 = grp2->bb_fragments ?
grp2->bb_free / grp2->bb_fragments : 0;
return (num_frags_2 - num_frags_1);
}
/*
* Reinsert grpinfo into the avg_fragment_size tree with new average
* fragment size.
*/
static void
mb_update_avg_fragment_size(struct super_block *sb, struct ext4_group_info *grp)
{
struct ext4_sb_info *sbi = EXT4_SB(sb);
if (!test_opt2(sb, MB_OPTIMIZE_SCAN) || grp->bb_free == 0)
return;
write_lock(&sbi->s_mb_rb_lock);
if (!RB_EMPTY_NODE(&grp->bb_avg_fragment_size_rb)) {
rb_erase(&grp->bb_avg_fragment_size_rb,
&sbi->s_mb_avg_fragment_size_root);
RB_CLEAR_NODE(&grp->bb_avg_fragment_size_rb);
}
ext4_mb_rb_insert(&sbi->s_mb_avg_fragment_size_root,
&grp->bb_avg_fragment_size_rb,
ext4_mb_avg_fragment_size_cmp);
write_unlock(&sbi->s_mb_rb_lock);
}
/*
* Choose next group by traversing largest_free_order lists. Updates *new_cr if
* cr level needs an update.
*/
static void ext4_mb_choose_next_group_cr0(struct ext4_allocation_context *ac,
int *new_cr, ext4_group_t *group, ext4_group_t ngroups)
{
struct ext4_sb_info *sbi = EXT4_SB(ac->ac_sb);
struct ext4_group_info *iter, *grp;
int i;
if (ac->ac_status == AC_STATUS_FOUND)
return;
if (unlikely(sbi->s_mb_stats && ac->ac_flags & EXT4_MB_CR0_OPTIMIZED))
atomic_inc(&sbi->s_bal_cr0_bad_suggestions);
grp = NULL;
for (i = ac->ac_2order; i < MB_NUM_ORDERS(ac->ac_sb); i++) {
if (list_empty(&sbi->s_mb_largest_free_orders[i]))
continue;
read_lock(&sbi->s_mb_largest_free_orders_locks[i]);
if (list_empty(&sbi->s_mb_largest_free_orders[i])) {
read_unlock(&sbi->s_mb_largest_free_orders_locks[i]);
continue;
}
grp = NULL;
list_for_each_entry(iter, &sbi->s_mb_largest_free_orders[i],
bb_largest_free_order_node) {
if (sbi->s_mb_stats)
atomic64_inc(&sbi->s_bal_cX_groups_considered[0]);
if (likely(ext4_mb_good_group(ac, iter->bb_group, 0))) {
grp = iter;
break;
}
}
read_unlock(&sbi->s_mb_largest_free_orders_locks[i]);
if (grp)
break;
}
if (!grp) {
/* Increment cr and search again */
*new_cr = 1;
} else {
*group = grp->bb_group;
ac->ac_last_optimal_group = *group;
ac->ac_flags |= EXT4_MB_CR0_OPTIMIZED;
}
}
/*
* Choose next group by traversing average fragment size tree. Updates *new_cr
* if cr lvel needs an update. Sets EXT4_MB_SEARCH_NEXT_LINEAR to indicate that
* the linear search should continue for one iteration since there's lock
* contention on the rb tree lock.
*/
static void ext4_mb_choose_next_group_cr1(struct ext4_allocation_context *ac,
int *new_cr, ext4_group_t *group, ext4_group_t ngroups)
{
struct ext4_sb_info *sbi = EXT4_SB(ac->ac_sb);
int avg_fragment_size, best_so_far;
struct rb_node *node, *found;
struct ext4_group_info *grp;
/*
* If there is contention on the lock, instead of waiting for the lock
* to become available, just continue searching lineraly. We'll resume
* our rb tree search later starting at ac->ac_last_optimal_group.
*/
if (!read_trylock(&sbi->s_mb_rb_lock)) {
ac->ac_flags |= EXT4_MB_SEARCH_NEXT_LINEAR;
return;
}
if (unlikely(ac->ac_flags & EXT4_MB_CR1_OPTIMIZED)) {
if (sbi->s_mb_stats)
atomic_inc(&sbi->s_bal_cr1_bad_suggestions);
/* We have found something at CR 1 in the past */
grp = ext4_get_group_info(ac->ac_sb, ac->ac_last_optimal_group);
for (found = rb_next(&grp->bb_avg_fragment_size_rb); found != NULL;
found = rb_next(found)) {
grp = rb_entry(found, struct ext4_group_info,
bb_avg_fragment_size_rb);
if (sbi->s_mb_stats)
atomic64_inc(&sbi->s_bal_cX_groups_considered[1]);
if (likely(ext4_mb_good_group(ac, grp->bb_group, 1)))
break;
}
goto done;
}
node = sbi->s_mb_avg_fragment_size_root.rb_node;
best_so_far = 0;
found = NULL;
while (node) {
grp = rb_entry(node, struct ext4_group_info,
bb_avg_fragment_size_rb);
avg_fragment_size = 0;
if (ext4_mb_good_group(ac, grp->bb_group, 1)) {
avg_fragment_size = grp->bb_fragments ?
grp->bb_free / grp->bb_fragments : 0;
if (!best_so_far || avg_fragment_size < best_so_far) {
best_so_far = avg_fragment_size;
found = node;
}
}
if (avg_fragment_size > ac->ac_g_ex.fe_len)
node = node->rb_right;
else
node = node->rb_left;
}
done:
if (found) {
grp = rb_entry(found, struct ext4_group_info,
bb_avg_fragment_size_rb);
*group = grp->bb_group;
ac->ac_flags |= EXT4_MB_CR1_OPTIMIZED;
} else {
*new_cr = 2;
}
read_unlock(&sbi->s_mb_rb_lock);
ac->ac_last_optimal_group = *group;
}
static inline int should_optimize_scan(struct ext4_allocation_context *ac)
{
if (unlikely(!test_opt2(ac->ac_sb, MB_OPTIMIZE_SCAN)))
return 0;
if (ac->ac_criteria >= 2)
return 0;
if (ext4_test_inode_flag(ac->ac_inode, EXT4_INODE_EXTENTS))
return 0;
return 1;
}
/*
* Return next linear group for allocation. If linear traversal should not be
* performed, this function just returns the same group
*/
static int
next_linear_group(struct ext4_allocation_context *ac, int group, int ngroups)
{
if (!should_optimize_scan(ac))
goto inc_and_return;
if (ac->ac_groups_linear_remaining) {
ac->ac_groups_linear_remaining--;
goto inc_and_return;
}
if (ac->ac_flags & EXT4_MB_SEARCH_NEXT_LINEAR) {
ac->ac_flags &= ~EXT4_MB_SEARCH_NEXT_LINEAR;
goto inc_and_return;
}
return group;
inc_and_return:
/*
* Artificially restricted ngroups for non-extent
* files makes group > ngroups possible on first loop.
*/
return group + 1 >= ngroups ? 0 : group + 1;
}
/*
* ext4_mb_choose_next_group: choose next group for allocation.
*
* @ac Allocation Context
* @new_cr This is an output parameter. If the there is no good group
* available at current CR level, this field is updated to indicate
* the new cr level that should be used.
* @group This is an input / output parameter. As an input it indicates the
* next group that the allocator intends to use for allocation. As
* output, this field indicates the next group that should be used as
* determined by the optimization functions.
* @ngroups Total number of groups
*/
static void ext4_mb_choose_next_group(struct ext4_allocation_context *ac,
int *new_cr, ext4_group_t *group, ext4_group_t ngroups)
{
*new_cr = ac->ac_criteria;
if (!should_optimize_scan(ac) || ac->ac_groups_linear_remaining)
return;
if (*new_cr == 0) {
ext4_mb_choose_next_group_cr0(ac, new_cr, group, ngroups);
} else if (*new_cr == 1) {
ext4_mb_choose_next_group_cr1(ac, new_cr, group, ngroups);
} else {
/*
* TODO: For CR=2, we can arrange groups in an rb tree sorted by
* bb_free. But until that happens, we should never come here.
*/
WARN_ON(1);
}
}
/*
* Cache the order of the largest free extent we have available in this block
* group.
*/
static void
mb_set_largest_free_order(struct super_block *sb, struct ext4_group_info *grp)
{
struct ext4_sb_info *sbi = EXT4_SB(sb);
int i;
if (test_opt2(sb, MB_OPTIMIZE_SCAN) && grp->bb_largest_free_order >= 0) {
write_lock(&sbi->s_mb_largest_free_orders_locks[
grp->bb_largest_free_order]);
list_del_init(&grp->bb_largest_free_order_node);
write_unlock(&sbi->s_mb_largest_free_orders_locks[
grp->bb_largest_free_order]);
}
grp->bb_largest_free_order = -1; /* uninit */
for (i = MB_NUM_ORDERS(sb) - 1; i >= 0; i--) {
if (grp->bb_counters[i] > 0) {
grp->bb_largest_free_order = i;
break;
}
}
if (test_opt2(sb, MB_OPTIMIZE_SCAN) &&
grp->bb_largest_free_order >= 0 && grp->bb_free) {
write_lock(&sbi->s_mb_largest_free_orders_locks[
grp->bb_largest_free_order]);
list_add_tail(&grp->bb_largest_free_order_node,
&sbi->s_mb_largest_free_orders[grp->bb_largest_free_order]);
write_unlock(&sbi->s_mb_largest_free_orders_locks[
grp->bb_largest_free_order]);
}
}
static noinline_for_stack
void ext4_mb_generate_buddy(struct super_block *sb,
void *buddy, void *bitmap, ext4_group_t group)
{
struct ext4_group_info *grp = ext4_get_group_info(sb, group);
struct ext4_sb_info *sbi = EXT4_SB(sb);
ext4_grpblk_t max = EXT4_CLUSTERS_PER_GROUP(sb);
ext4_grpblk_t i = 0;
ext4_grpblk_t first;
ext4_grpblk_t len;
unsigned free = 0;
unsigned fragments = 0;
unsigned long long period = get_cycles();
/* initialize buddy from bitmap which is aggregation
* of on-disk bitmap and preallocations */
i = mb_find_next_zero_bit(bitmap, max, 0);
grp->bb_first_free = i;
while (i < max) {
fragments++;
first = i;
i = mb_find_next_bit(bitmap, max, i);
len = i - first;
free += len;
if (len > 1)
ext4_mb_mark_free_simple(sb, buddy, first, len, grp);
else
grp->bb_counters[0]++;
if (i < max)
i = mb_find_next_zero_bit(bitmap, max, i);
}
grp->bb_fragments = fragments;
if (free != grp->bb_free) {
ext4_grp_locked_error(sb, group, 0, 0,
"block bitmap and bg descriptor "
"inconsistent: %u vs %u free clusters",
free, grp->bb_free);
/*
* If we intend to continue, we consider group descriptor
* corrupt and update bb_free using bitmap value
*/
grp->bb_free = free;
ext4_mark_group_bitmap_corrupted(sb, group,
EXT4_GROUP_INFO_BBITMAP_CORRUPT);
}
mb_set_largest_free_order(sb, grp);
clear_bit(EXT4_GROUP_INFO_NEED_INIT_BIT, &(grp->bb_state));
period = get_cycles() - period;
atomic_inc(&sbi->s_mb_buddies_generated);
atomic64_add(period, &sbi->s_mb_generation_time);
mb_update_avg_fragment_size(sb, grp);
}
/* The buddy information is attached the buddy cache inode
* for convenience. The information regarding each group
* is loaded via ext4_mb_load_buddy. The information involve
* block bitmap and buddy information. The information are
* stored in the inode as
*
* { page }
* [ group 0 bitmap][ group 0 buddy] [group 1][ group 1]...
*
*
* one block each for bitmap and buddy information.
* So for each group we take up 2 blocks. A page can
* contain blocks_per_page (PAGE_SIZE / blocksize) blocks.
* So it can have information regarding groups_per_page which
* is blocks_per_page/2
*
* Locking note: This routine takes the block group lock of all groups
* for this page; do not hold this lock when calling this routine!
*/
static int ext4_mb_init_cache(struct page *page, char *incore, gfp_t gfp)
{
ext4_group_t ngroups;
int blocksize;
int blocks_per_page;
int groups_per_page;
int err = 0;
int i;
ext4_group_t first_group, group;
int first_block;
struct super_block *sb;
struct buffer_head *bhs;
struct buffer_head **bh = NULL;
struct inode *inode;
char *data;
char *bitmap;
struct ext4_group_info *grinfo;
inode = page->mapping->host;
sb = inode->i_sb;
ngroups = ext4_get_groups_count(sb);
blocksize = i_blocksize(inode);
blocks_per_page = PAGE_SIZE / blocksize;
mb_debug(sb, "init page %lu\n", page->index);
groups_per_page = blocks_per_page >> 1;
if (groups_per_page == 0)
groups_per_page = 1;
/* allocate buffer_heads to read bitmaps */
if (groups_per_page > 1) {
i = sizeof(struct buffer_head *) * groups_per_page;
bh = kzalloc(i, gfp);
if (bh == NULL) {
err = -ENOMEM;
goto out;
}
} else
bh = &bhs;
first_group = page->index * blocks_per_page / 2;
/* read all groups the page covers into the cache */
for (i = 0, group = first_group; i < groups_per_page; i++, group++) {
if (group >= ngroups)
break;
grinfo = ext4_get_group_info(sb, group);
/*
* If page is uptodate then we came here after online resize
* which added some new uninitialized group info structs, so
* we must skip all initialized uptodate buddies on the page,
* which may be currently in use by an allocating task.
*/
if (PageUptodate(page) && !EXT4_MB_GRP_NEED_INIT(grinfo)) {
bh[i] = NULL;
continue;
}
bh[i] = ext4_read_block_bitmap_nowait(sb, group, false);
if (IS_ERR(bh[i])) {
err = PTR_ERR(bh[i]);
bh[i] = NULL;
goto out;
}
mb_debug(sb, "read bitmap for group %u\n", group);
}
/* wait for I/O completion */
for (i = 0, group = first_group; i < groups_per_page; i++, group++) {
int err2;
if (!bh[i])
continue;
err2 = ext4_wait_block_bitmap(sb, group, bh[i]);
if (!err)
err = err2;
}
first_block = page->index * blocks_per_page;
for (i = 0; i < blocks_per_page; i++) {
group = (first_block + i) >> 1;
if (group >= ngroups)
break;
if (!bh[group - first_group])
/* skip initialized uptodate buddy */
continue;
if (!buffer_verified(bh[group - first_group]))
/* Skip faulty bitmaps */
continue;
err = 0;
/*
* data carry information regarding this
* particular group in the format specified
* above
*
*/
data = page_address(page) + (i * blocksize);
bitmap = bh[group - first_group]->b_data;
/*
* We place the buddy block and bitmap block
* close together
*/
if ((first_block + i) & 1) {
/* this is block of buddy */
BUG_ON(incore == NULL);
mb_debug(sb, "put buddy for group %u in page %lu/%x\n",
group, page->index, i * blocksize);
trace_ext4_mb_buddy_bitmap_load(sb, group);
grinfo = ext4_get_group_info(sb, group);
grinfo->bb_fragments = 0;
memset(grinfo->bb_counters, 0,
sizeof(*grinfo->bb_counters) *
(MB_NUM_ORDERS(sb)));
/*
* incore got set to the group block bitmap below
*/
ext4_lock_group(sb, group);
/* init the buddy */
memset(data, 0xff, blocksize);
ext4_mb_generate_buddy(sb, data, incore, group);
ext4_unlock_group(sb, group);
incore = NULL;
} else {
/* this is block of bitmap */
BUG_ON(incore != NULL);
mb_debug(sb, "put bitmap for group %u in page %lu/%x\n",
group, page->index, i * blocksize);
trace_ext4_mb_bitmap_load(sb, group);
/* see comments in ext4_mb_put_pa() */
ext4_lock_group(sb, group);
memcpy(data, bitmap, blocksize);
/* mark all preallocated blks used in in-core bitmap */
ext4_mb_generate_from_pa(sb, data, group);
ext4_mb_generate_from_freelist(sb, data, group);
ext4_unlock_group(sb, group);
/* set incore so that the buddy information can be
* generated using this
*/
incore = data;
}
}
SetPageUptodate(page);
out:
if (bh) {
for (i = 0; i < groups_per_page; i++)
brelse(bh[i]);
if (bh != &bhs)
kfree(bh);
}
return err;
}
/*
* Lock the buddy and bitmap pages. This make sure other parallel init_group
* on the same buddy page doesn't happen whild holding the buddy page lock.
* Return locked buddy and bitmap pages on e4b struct. If buddy and bitmap
* are on the same page e4b->bd_buddy_page is NULL and return value is 0.
*/
static int ext4_mb_get_buddy_page_lock(struct super_block *sb,
ext4_group_t group, struct ext4_buddy *e4b, gfp_t gfp)
{
struct inode *inode = EXT4_SB(sb)->s_buddy_cache;
int block, pnum, poff;
int blocks_per_page;
struct page *page;
e4b->bd_buddy_page = NULL;
e4b->bd_bitmap_page = NULL;
blocks_per_page = PAGE_SIZE / sb->s_blocksize;
/*
* the buddy cache inode stores the block bitmap
* and buddy information in consecutive blocks.
* So for each group we need two blocks.
*/
block = group * 2;
pnum = block / blocks_per_page;
poff = block % blocks_per_page;
page = find_or_create_page(inode->i_mapping, pnum, gfp);
if (!page)
return -ENOMEM;
BUG_ON(page->mapping != inode->i_mapping);
e4b->bd_bitmap_page = page;
e4b->bd_bitmap = page_address(page) + (poff * sb->s_blocksize);
if (blocks_per_page >= 2) {
/* buddy and bitmap are on the same page */
return 0;
}
block++;
pnum = block / blocks_per_page;
page = find_or_create_page(inode->i_mapping, pnum, gfp);
if (!page)
return -ENOMEM;
BUG_ON(page->mapping != inode->i_mapping);
e4b->bd_buddy_page = page;
return 0;
}
static void ext4_mb_put_buddy_page_lock(struct ext4_buddy *e4b)
{
if (e4b->bd_bitmap_page) {
unlock_page(e4b->bd_bitmap_page);
put_page(e4b->bd_bitmap_page);
}
if (e4b->bd_buddy_page) {
unlock_page(e4b->bd_buddy_page);
put_page(e4b->bd_buddy_page);
}
}
/*
* Locking note: This routine calls ext4_mb_init_cache(), which takes the
* block group lock of all groups for this page; do not hold the BG lock when
* calling this routine!
*/
static noinline_for_stack
int ext4_mb_init_group(struct super_block *sb, ext4_group_t group, gfp_t gfp)
{
struct ext4_group_info *this_grp;
struct ext4_buddy e4b;
struct page *page;
int ret = 0;
might_sleep();
mb_debug(sb, "init group %u\n", group);
this_grp = ext4_get_group_info(sb, group);
/*
* This ensures that we don't reinit the buddy cache
* page which map to the group from which we are already
* allocating. If we are looking at the buddy cache we would
* have taken a reference using ext4_mb_load_buddy and that
* would have pinned buddy page to page cache.
* The call to ext4_mb_get_buddy_page_lock will mark the
* page accessed.
*/
ret = ext4_mb_get_buddy_page_lock(sb, group, &e4b, gfp);
if (ret || !EXT4_MB_GRP_NEED_INIT(this_grp)) {
/*
* somebody initialized the group
* return without doing anything
*/
goto err;
}
page = e4b.bd_bitmap_page;
ret = ext4_mb_init_cache(page, NULL, gfp);
if (ret)
goto err;
if (!PageUptodate(page)) {
ret = -EIO;
goto err;
}
if (e4b.bd_buddy_page == NULL) {
/*
* If both the bitmap and buddy are in
* the same page we don't need to force
* init the buddy
*/
ret = 0;
goto err;
}
/* init buddy cache */
page = e4b.bd_buddy_page;
ret = ext4_mb_init_cache(page, e4b.bd_bitmap, gfp);
if (ret)
goto err;
if (!PageUptodate(page)) {
ret = -EIO;
goto err;
}
err:
ext4_mb_put_buddy_page_lock(&e4b);
return ret;
}
/*
* Locking note: This routine calls ext4_mb_init_cache(), which takes the
* block group lock of all groups for this page; do not hold the BG lock when
* calling this routine!
*/
static noinline_for_stack int
ext4_mb_load_buddy_gfp(struct super_block *sb, ext4_group_t group,
struct ext4_buddy *e4b, gfp_t gfp)
{
int blocks_per_page;
int block;
int pnum;
int poff;
struct page *page;
int ret;
struct ext4_group_info *grp;
struct ext4_sb_info *sbi = EXT4_SB(sb);
struct inode *inode = sbi->s_buddy_cache;
might_sleep();
mb_debug(sb, "load group %u\n", group);
blocks_per_page = PAGE_SIZE / sb->s_blocksize;
grp = ext4_get_group_info(sb, group);
e4b->bd_blkbits = sb->s_blocksize_bits;
e4b->bd_info = grp;
e4b->bd_sb = sb;
e4b->bd_group = group;
e4b->bd_buddy_page = NULL;
e4b->bd_bitmap_page = NULL;
if (unlikely(EXT4_MB_GRP_NEED_INIT(grp))) {
/*
* we need full data about the group
* to make a good selection
*/
ret = ext4_mb_init_group(sb, group, gfp);
if (ret)
return ret;
}
/*
* the buddy cache inode stores the block bitmap
* and buddy information in consecutive blocks.
* So for each group we need two blocks.
*/
block = group * 2;
pnum = block / blocks_per_page;
poff = block % blocks_per_page;
/* we could use find_or_create_page(), but it locks page
* what we'd like to avoid in fast path ... */
page = find_get_page_flags(inode->i_mapping, pnum, FGP_ACCESSED);
if (page == NULL || !PageUptodate(page)) {
if (page)
/*
* drop the page reference and try
* to get the page with lock. If we
* are not uptodate that implies
* somebody just created the page but
* is yet to initialize the same. So
* wait for it to initialize.
*/
put_page(page);
page = find_or_create_page(inode->i_mapping, pnum, gfp);
if (page) {
BUG_ON(page->mapping != inode->i_mapping);
if (!PageUptodate(page)) {
ret = ext4_mb_init_cache(page, NULL, gfp);
if (ret) {
unlock_page(page);
goto err;
}
mb_cmp_bitmaps(e4b, page_address(page) +
(poff * sb->s_blocksize));
}
unlock_page(page);
}
}
if (page == NULL) {
ret = -ENOMEM;
goto err;
}
if (!PageUptodate(page)) {
ret = -EIO;
goto err;
}
/* Pages marked accessed already */
e4b->bd_bitmap_page = page;
e4b->bd_bitmap = page_address(page) + (poff * sb->s_blocksize);
block++;
pnum = block / blocks_per_page;
poff = block % blocks_per_page;
page = find_get_page_flags(inode->i_mapping, pnum, FGP_ACCESSED);
if (page == NULL || !PageUptodate(page)) {
if (page)
put_page(page);
page = find_or_create_page(inode->i_mapping, pnum, gfp);
if (page) {
BUG_ON(page->mapping != inode->i_mapping);
if (!PageUptodate(page)) {
ret = ext4_mb_init_cache(page, e4b->bd_bitmap,
gfp);
if (ret) {
unlock_page(page);
goto err;
}
}
unlock_page(page);
}
}
if (page == NULL) {
ret = -ENOMEM;
goto err;
}
if (!PageUptodate(page)) {
ret = -EIO;
goto err;
}
/* Pages marked accessed already */
e4b->bd_buddy_page = page;
e4b->bd_buddy = page_address(page) + (poff * sb->s_blocksize);
return 0;
err:
if (page)
put_page(page);
if (e4b->bd_bitmap_page)
put_page(e4b->bd_bitmap_page);
if (e4b->bd_buddy_page)
put_page(e4b->bd_buddy_page);
e4b->bd_buddy = NULL;
e4b->bd_bitmap = NULL;
return ret;
}
static int ext4_mb_load_buddy(struct super_block *sb, ext4_group_t group,
struct ext4_buddy *e4b)
{
return ext4_mb_load_buddy_gfp(sb, group, e4b, GFP_NOFS);
}
static void ext4_mb_unload_buddy(struct ext4_buddy *e4b)
{
if (e4b->bd_bitmap_page)
put_page(e4b->bd_bitmap_page);
if (e4b->bd_buddy_page)
put_page(e4b->bd_buddy_page);
}
static int mb_find_order_for_block(struct ext4_buddy *e4b, int block)
{
int order = 1, max;
void *bb;
BUG_ON(e4b->bd_bitmap == e4b->bd_buddy);
BUG_ON(block >= (1 << (e4b->bd_blkbits + 3)));
while (order <= e4b->bd_blkbits + 1) {
bb = mb_find_buddy(e4b, order, &max);
if (!mb_test_bit(block >> order, bb)) {
/* this block is part of buddy of order 'order' */
return order;
}
order++;
}
return 0;
}
static void mb_clear_bits(void *bm, int cur, int len)
{
__u32 *addr;
len = cur + len;
while (cur < len) {
if ((cur & 31) == 0 && (len - cur) >= 32) {
/* fast path: clear whole word at once */
addr = bm + (cur >> 3);
*addr = 0;
cur += 32;
continue;
}
mb_clear_bit(cur, bm);
cur++;
}
}
/* clear bits in given range
* will return first found zero bit if any, -1 otherwise
*/
static int mb_test_and_clear_bits(void *bm, int cur, int len)
{
__u32 *addr;
int zero_bit = -1;
len = cur + len;
while (cur < len) {
if ((cur & 31) == 0 && (len - cur) >= 32) {
/* fast path: clear whole word at once */
addr = bm + (cur >> 3);
if (*addr != (__u32)(-1) && zero_bit == -1)
zero_bit = cur + mb_find_next_zero_bit(addr, 32, 0);
*addr = 0;
cur += 32;
continue;
}
if (!mb_test_and_clear_bit(cur, bm) && zero_bit == -1)
zero_bit = cur;
cur++;
}
return zero_bit;
}
void ext4_set_bits(void *bm, int cur, int len)
{
__u32 *addr;
len = cur + len;
while (cur < len) {
if ((cur & 31) == 0 && (len - cur) >= 32) {
/* fast path: set whole word at once */
addr = bm + (cur >> 3);
*addr = 0xffffffff;
cur += 32;
continue;
}
mb_set_bit(cur, bm);
cur++;
}
}
static inline int mb_buddy_adjust_border(int* bit, void* bitmap, int side)
{
if (mb_test_bit(*bit + side, bitmap)) {
mb_clear_bit(*bit, bitmap);
(*bit) -= side;
return 1;
}
else {
(*bit) += side;
mb_set_bit(*bit, bitmap);
return -1;
}
}
static void mb_buddy_mark_free(struct ext4_buddy *e4b, int first, int last)
{
int max;
int order = 1;
void *buddy = mb_find_buddy(e4b, order, &max);
while (buddy) {
void *buddy2;
/* Bits in range [first; last] are known to be set since
* corresponding blocks were allocated. Bits in range
* (first; last) will stay set because they form buddies on
* upper layer. We just deal with borders if they don't
* align with upper layer and then go up.
* Releasing entire group is all about clearing
* single bit of highest order buddy.
*/
/* Example:
* ---------------------------------
* | 1 | 1 | 1 | 1 |
* ---------------------------------
* | 0 | 1 | 1 | 1 | 1 | 1 | 1 | 1 |
* ---------------------------------
* 0 1 2 3 4 5 6 7
* \_____________________/
*
* Neither [1] nor [6] is aligned to above layer.
* Left neighbour [0] is free, so mark it busy,
* decrease bb_counters and extend range to
* [0; 6]
* Right neighbour [7] is busy. It can't be coaleasced with [6], so
* mark [6] free, increase bb_counters and shrink range to
* [0; 5].
* Then shift range to [0; 2], go up and do the same.
*/
if (first & 1)
e4b->bd_info->bb_counters[order] += mb_buddy_adjust_border(&first, buddy, -1);
if (!(last & 1))
e4b->bd_info->bb_counters[order] += mb_buddy_adjust_border(&last, buddy, 1);
if (first > last)
break;
order++;
if (first == last || !(buddy2 = mb_find_buddy(e4b, order, &max))) {
mb_clear_bits(buddy, first, last - first + 1);
e4b->bd_info->bb_counters[order - 1] += last - first + 1;
break;
}
first >>= 1;
last >>= 1;
buddy = buddy2;
}
}
static void mb_free_blocks(struct inode *inode, struct ext4_buddy *e4b,
int first, int count)
{
int left_is_free = 0;
int right_is_free = 0;
int block;
int last = first + count - 1;
struct super_block *sb = e4b->bd_sb;
if (WARN_ON(count == 0))
return;
BUG_ON(last >= (sb->s_blocksize << 3));
assert_spin_locked(ext4_group_lock_ptr(sb, e4b->bd_group));
/* Don't bother if the block group is corrupt. */
if (unlikely(EXT4_MB_GRP_BBITMAP_CORRUPT(e4b->bd_info)))
return;
mb_check_buddy(e4b);
mb_free_blocks_double(inode, e4b, first, count);
this_cpu_inc(discard_pa_seq);
e4b->bd_info->bb_free += count;
if (first < e4b->bd_info->bb_first_free)
e4b->bd_info->bb_first_free = first;
/* access memory sequentially: check left neighbour,
* clear range and then check right neighbour
*/
if (first != 0)
left_is_free = !mb_test_bit(first - 1, e4b->bd_bitmap);
block = mb_test_and_clear_bits(e4b->bd_bitmap, first, count);
if (last + 1 < EXT4_SB(sb)->s_mb_maxs[0])
right_is_free = !mb_test_bit(last + 1, e4b->bd_bitmap);
if (unlikely(block != -1)) {
struct ext4_sb_info *sbi = EXT4_SB(sb);
ext4_fsblk_t blocknr;
blocknr = ext4_group_first_block_no(sb, e4b->bd_group);
blocknr += EXT4_C2B(sbi, block);
if (!(sbi->s_mount_state & EXT4_FC_REPLAY)) {
ext4_grp_locked_error(sb, e4b->bd_group,
inode ? inode->i_ino : 0,
blocknr,
"freeing already freed block (bit %u); block bitmap corrupt.",
block);
ext4_mark_group_bitmap_corrupted(
sb, e4b->bd_group,
EXT4_GROUP_INFO_BBITMAP_CORRUPT);
}
goto done;
}
/* let's maintain fragments counter */
if (left_is_free && right_is_free)
e4b->bd_info->bb_fragments--;
else if (!left_is_free && !right_is_free)
e4b->bd_info->bb_fragments++;
/* buddy[0] == bd_bitmap is a special case, so handle
* it right away and let mb_buddy_mark_free stay free of
* zero order checks.
* Check if neighbours are to be coaleasced,
* adjust bitmap bb_counters and borders appropriately.
*/
if (first & 1) {
first += !left_is_free;
e4b->bd_info->bb_counters[0] += left_is_free ? -1 : 1;
}
if (!(last & 1)) {
last -= !right_is_free;
e4b->bd_info->bb_counters[0] += right_is_free ? -1 : 1;
}
if (first <= last)
mb_buddy_mark_free(e4b, first >> 1, last >> 1);
done:
mb_set_largest_free_order(sb, e4b->bd_info);
mb_update_avg_fragment_size(sb, e4b->bd_info);
mb_check_buddy(e4b);
}
static int mb_find_extent(struct ext4_buddy *e4b, int block,
int needed, struct ext4_free_extent *ex)
{
int next = block;
int max, order;
void *buddy;
assert_spin_locked(ext4_group_lock_ptr(e4b->bd_sb, e4b->bd_group));
BUG_ON(ex == NULL);
buddy = mb_find_buddy(e4b, 0, &max);
BUG_ON(buddy == NULL);
BUG_ON(block >= max);
if (mb_test_bit(block, buddy)) {
ex->fe_len = 0;
ex->fe_start = 0;
ex->fe_group = 0;
return 0;
}
/* find actual order */
order = mb_find_order_for_block(e4b, block);
block = block >> order;
ex->fe_len = 1 << order;
ex->fe_start = block << order;
ex->fe_group = e4b->bd_group;
/* calc difference from given start */
next = next - ex->fe_start;
ex->fe_len -= next;
ex->fe_start += next;
while (needed > ex->fe_len &&
mb_find_buddy(e4b, order, &max)) {
if (block + 1 >= max)
break;
next = (block + 1) * (1 << order);
if (mb_test_bit(next, e4b->bd_bitmap))
break;
order = mb_find_order_for_block(e4b, next);
block = next >> order;
ex->fe_len += 1 << order;
}
if (ex->fe_start + ex->fe_len > EXT4_CLUSTERS_PER_GROUP(e4b->bd_sb)) {
/* Should never happen! (but apparently sometimes does?!?) */
WARN_ON(1);
ext4_grp_locked_error(e4b->bd_sb, e4b->bd_group, 0, 0,
"corruption or bug in mb_find_extent "
"block=%d, order=%d needed=%d ex=%u/%d/%d@%u",
block, order, needed, ex->fe_group, ex->fe_start,
ex->fe_len, ex->fe_logical);
ex->fe_len = 0;
ex->fe_start = 0;
ex->fe_group = 0;
}
return ex->fe_len;
}
static int mb_mark_used(struct ext4_buddy *e4b, struct ext4_free_extent *ex)
{
int ord;
int mlen = 0;
int max = 0;
int cur;
int start = ex->fe_start;
int len = ex->fe_len;
unsigned ret = 0;
int len0 = len;
void *buddy;
BUG_ON(start + len > (e4b->bd_sb->s_blocksize << 3));
BUG_ON(e4b->bd_group != ex->fe_group);
assert_spin_locked(ext4_group_lock_ptr(e4b->bd_sb, e4b->bd_group));
mb_check_buddy(e4b);
mb_mark_used_double(e4b, start, len);
this_cpu_inc(discard_pa_seq);
e4b->bd_info->bb_free -= len;
if (e4b->bd_info->bb_first_free == start)
e4b->bd_info->bb_first_free += len;
/* let's maintain fragments counter */
if (start != 0)
mlen = !mb_test_bit(start - 1, e4b->bd_bitmap);
if (start + len < EXT4_SB(e4b->bd_sb)->s_mb_maxs[0])
max = !mb_test_bit(start + len, e4b->bd_bitmap);
if (mlen && max)
e4b->bd_info->bb_fragments++;
else if (!mlen && !max)
e4b->bd_info->bb_fragments--;
/* let's maintain buddy itself */
while (len) {
ord = mb_find_order_for_block(e4b, start);
if (((start >> ord) << ord) == start && len >= (1 << ord)) {
/* the whole chunk may be allocated at once! */
mlen = 1 << ord;
buddy = mb_find_buddy(e4b, ord, &max);
BUG_ON((start >> ord) >= max);
mb_set_bit(start >> ord, buddy);
e4b->bd_info->bb_counters[ord]--;
start += mlen;
len -= mlen;
BUG_ON(len < 0);
continue;
}
/* store for history */
if (ret == 0)
ret = len | (ord << 16);
/* we have to split large buddy */
BUG_ON(ord <= 0);
buddy = mb_find_buddy(e4b, ord, &max);
mb_set_bit(start >> ord, buddy);
e4b->bd_info->bb_counters[ord]--;
ord--;
cur = (start >> ord) & ~1U;
buddy = mb_find_buddy(e4b, ord, &max);
mb_clear_bit(cur, buddy);
mb_clear_bit(cur + 1, buddy);
e4b->bd_info->bb_counters[ord]++;
e4b->bd_info->bb_counters[ord]++;
}
mb_set_largest_free_order(e4b->bd_sb, e4b->bd_info);
mb_update_avg_fragment_size(e4b->bd_sb, e4b->bd_info);
ext4_set_bits(e4b->bd_bitmap, ex->fe_start, len0);
mb_check_buddy(e4b);
return ret;
}
/*
* Must be called under group lock!
*/
static void ext4_mb_use_best_found(struct ext4_allocation_context *ac,
struct ext4_buddy *e4b)
{
struct ext4_sb_info *sbi = EXT4_SB(ac->ac_sb);
int ret;
BUG_ON(ac->ac_b_ex.fe_group != e4b->bd_group);
BUG_ON(ac->ac_status == AC_STATUS_FOUND);
ac->ac_b_ex.fe_len = min(ac->ac_b_ex.fe_len, ac->ac_g_ex.fe_len);
ac->ac_b_ex.fe_logical = ac->ac_g_ex.fe_logical;
ret = mb_mark_used(e4b, &ac->ac_b_ex);
/* preallocation can change ac_b_ex, thus we store actually
* allocated blocks for history */
ac->ac_f_ex = ac->ac_b_ex;
ac->ac_status = AC_STATUS_FOUND;
ac->ac_tail = ret & 0xffff;
ac->ac_buddy = ret >> 16;
/*
* take the page reference. We want the page to be pinned
* so that we don't get a ext4_mb_init_cache_call for this
* group until we update the bitmap. That would mean we
* double allocate blocks. The reference is dropped
* in ext4_mb_release_context
*/
ac->ac_bitmap_page = e4b->bd_bitmap_page;
get_page(ac->ac_bitmap_page);
ac->ac_buddy_page = e4b->bd_buddy_page;
get_page(ac->ac_buddy_page);
/* store last allocated for subsequent stream allocation */
if (ac->ac_flags & EXT4_MB_STREAM_ALLOC) {
spin_lock(&sbi->s_md_lock);
sbi->s_mb_last_group = ac->ac_f_ex.fe_group;
sbi->s_mb_last_start = ac->ac_f_ex.fe_start;
spin_unlock(&sbi->s_md_lock);
}
/*
* As we've just preallocated more space than
* user requested originally, we store allocated
* space in a special descriptor.
*/
if (ac->ac_o_ex.fe_len < ac->ac_b_ex.fe_len)
ext4_mb_new_preallocation(ac);
}
static void ext4_mb_check_limits(struct ext4_allocation_context *ac,
struct ext4_buddy *e4b,
int finish_group)
{
struct ext4_sb_info *sbi = EXT4_SB(ac->ac_sb);
struct ext4_free_extent *bex = &ac->ac_b_ex;
struct ext4_free_extent *gex = &ac->ac_g_ex;
struct ext4_free_extent ex;
int max;
if (ac->ac_status == AC_STATUS_FOUND)
return;
/*
* We don't want to scan for a whole year
*/
if (ac->ac_found > sbi->s_mb_max_to_scan &&
!(ac->ac_flags & EXT4_MB_HINT_FIRST)) {
ac->ac_status = AC_STATUS_BREAK;
return;
}
/*
* Haven't found good chunk so far, let's continue
*/
if (bex->fe_len < gex->fe_len)
return;
if ((finish_group || ac->ac_found > sbi->s_mb_min_to_scan)
&& bex->fe_group == e4b->bd_group) {
/* recheck chunk's availability - we don't know
* when it was found (within this lock-unlock
* period or not) */
max = mb_find_extent(e4b, bex->fe_start, gex->fe_len, &ex);
if (max >= gex->fe_len) {
ext4_mb_use_best_found(ac, e4b);
return;
}
}
}
/*
* The routine checks whether found extent is good enough. If it is,
* then the extent gets marked used and flag is set to the context
* to stop scanning. Otherwise, the extent is compared with the
* previous found extent and if new one is better, then it's stored
* in the context. Later, the best found extent will be used, if
* mballoc can't find good enough extent.
*
* FIXME: real allocation policy is to be designed yet!
*/
static void ext4_mb_measure_extent(struct ext4_allocation_context *ac,
struct ext4_free_extent *ex,
struct ext4_buddy *e4b)
{
struct ext4_free_extent *bex = &ac->ac_b_ex;
struct ext4_free_extent *gex = &ac->ac_g_ex;
BUG_ON(ex->fe_len <= 0);
BUG_ON(ex->fe_len > EXT4_CLUSTERS_PER_GROUP(ac->ac_sb));
BUG_ON(ex->fe_start >= EXT4_CLUSTERS_PER_GROUP(ac->ac_sb));
BUG_ON(ac->ac_status != AC_STATUS_CONTINUE);
ac->ac_found++;
/*
* The special case - take what you catch first
*/
if (unlikely(ac->ac_flags & EXT4_MB_HINT_FIRST)) {
*bex = *ex;
ext4_mb_use_best_found(ac, e4b);
return;
}
/*
* Let's check whether the chuck is good enough
*/
if (ex->fe_len == gex->fe_len) {
*bex = *ex;
ext4_mb_use_best_found(ac, e4b);
return;
}
/*
* If this is first found extent, just store it in the context
*/
if (bex->fe_len == 0) {
*bex = *ex;
return;
}
/*
* If new found extent is better, store it in the context
*/
if (bex->fe_len < gex->fe_len) {
/* if the request isn't satisfied, any found extent
* larger than previous best one is better */
if (ex->fe_len > bex->fe_len)
*bex = *ex;
} else if (ex->fe_len > gex->fe_len) {
/* if the request is satisfied, then we try to find
* an extent that still satisfy the request, but is
* smaller than previous one */
if (ex->fe_len < bex->fe_len)
*bex = *ex;
}
ext4_mb_check_limits(ac, e4b, 0);
}
static noinline_for_stack
int ext4_mb_try_best_found(struct ext4_allocation_context *ac,
struct ext4_buddy *e4b)
{
struct ext4_free_extent ex = ac->ac_b_ex;
ext4_group_t group = ex.fe_group;
int max;
int err;
BUG_ON(ex.fe_len <= 0);
err = ext4_mb_load_buddy(ac->ac_sb, group, e4b);
if (err)
return err;
ext4_lock_group(ac->ac_sb, group);
max = mb_find_extent(e4b, ex.fe_start, ex.fe_len, &ex);
if (max > 0) {
ac->ac_b_ex = ex;
ext4_mb_use_best_found(ac, e4b);
}
ext4_unlock_group(ac->ac_sb, group);
ext4_mb_unload_buddy(e4b);
return 0;
}
static noinline_for_stack
int ext4_mb_find_by_goal(struct ext4_allocation_context *ac,
struct ext4_buddy *e4b)
{
ext4_group_t group = ac->ac_g_ex.fe_group;
int max;
int err;
struct ext4_sb_info *sbi = EXT4_SB(ac->ac_sb);
struct ext4_group_info *grp = ext4_get_group_info(ac->ac_sb, group);
struct ext4_free_extent ex;
if (!(ac->ac_flags & EXT4_MB_HINT_TRY_GOAL))
return 0;
if (grp->bb_free == 0)
return 0;
err = ext4_mb_load_buddy(ac->ac_sb, group, e4b);
if (err)
return err;
if (unlikely(EXT4_MB_GRP_BBITMAP_CORRUPT(e4b->bd_info))) {
ext4_mb_unload_buddy(e4b);
return 0;
}
ext4_lock_group(ac->ac_sb, group);
max = mb_find_extent(e4b, ac->ac_g_ex.fe_start,
ac->ac_g_ex.fe_len, &ex);
ex.fe_logical = 0xDEADFA11; /* debug value */
if (max >= ac->ac_g_ex.fe_len && ac->ac_g_ex.fe_len == sbi->s_stripe) {
ext4_fsblk_t start;
start = ext4_group_first_block_no(ac->ac_sb, e4b->bd_group) +
ex.fe_start;
/* use do_div to get remainder (would be 64-bit modulo) */
if (do_div(start, sbi->s_stripe) == 0) {
ac->ac_found++;
ac->ac_b_ex = ex;
ext4_mb_use_best_found(ac, e4b);
}
} else if (max >= ac->ac_g_ex.fe_len) {
BUG_ON(ex.fe_len <= 0);
BUG_ON(ex.fe_group != ac->ac_g_ex.fe_group);
BUG_ON(ex.fe_start != ac->ac_g_ex.fe_start);
ac->ac_found++;
ac->ac_b_ex = ex;
ext4_mb_use_best_found(ac, e4b);
} else if (max > 0 && (ac->ac_flags & EXT4_MB_HINT_MERGE)) {
/* Sometimes, caller may want to merge even small
* number of blocks to an existing extent */
BUG_ON(ex.fe_len <= 0);
BUG_ON(ex.fe_group != ac->ac_g_ex.fe_group);
BUG_ON(ex.fe_start != ac->ac_g_ex.fe_start);
ac->ac_found++;
ac->ac_b_ex = ex;
ext4_mb_use_best_found(ac, e4b);
}
ext4_unlock_group(ac->ac_sb, group);
ext4_mb_unload_buddy(e4b);
return 0;
}
/*
* The routine scans buddy structures (not bitmap!) from given order
* to max order and tries to find big enough chunk to satisfy the req
*/
static noinline_for_stack
void ext4_mb_simple_scan_group(struct ext4_allocation_context *ac,
struct ext4_buddy *e4b)
{
struct super_block *sb = ac->ac_sb;
struct ext4_group_info *grp = e4b->bd_info;
void *buddy;
int i;
int k;
int max;
BUG_ON(ac->ac_2order <= 0);
for (i = ac->ac_2order; i < MB_NUM_ORDERS(sb); i++) {
if (grp->bb_counters[i] == 0)
continue;
buddy = mb_find_buddy(e4b, i, &max);
BUG_ON(buddy == NULL);
k = mb_find_next_zero_bit(buddy, max, 0);
if (k >= max) {
ext4_grp_locked_error(ac->ac_sb, e4b->bd_group, 0, 0,
"%d free clusters of order %d. But found 0",
grp->bb_counters[i], i);
ext4_mark_group_bitmap_corrupted(ac->ac_sb,
e4b->bd_group,
EXT4_GROUP_INFO_BBITMAP_CORRUPT);
break;
}
ac->ac_found++;
ac->ac_b_ex.fe_len = 1 << i;
ac->ac_b_ex.fe_start = k << i;
ac->ac_b_ex.fe_group = e4b->bd_group;
ext4_mb_use_best_found(ac, e4b);
BUG_ON(ac->ac_f_ex.fe_len != ac->ac_g_ex.fe_len);
if (EXT4_SB(sb)->s_mb_stats)
atomic_inc(&EXT4_SB(sb)->s_bal_2orders);
break;
}
}
/*
* The routine scans the group and measures all found extents.
* In order to optimize scanning, caller must pass number of
* free blocks in the group, so the routine can know upper limit.
*/
static noinline_for_stack
void ext4_mb_complex_scan_group(struct ext4_allocation_context *ac,
struct ext4_buddy *e4b)
{
struct super_block *sb = ac->ac_sb;
void *bitmap = e4b->bd_bitmap;
struct ext4_free_extent ex;
int i;
int free;
free = e4b->bd_info->bb_free;
if (WARN_ON(free <= 0))
return;
i = e4b->bd_info->bb_first_free;
while (free && ac->ac_status == AC_STATUS_CONTINUE) {
i = mb_find_next_zero_bit(bitmap,
EXT4_CLUSTERS_PER_GROUP(sb), i);
if (i >= EXT4_CLUSTERS_PER_GROUP(sb)) {
/*
* IF we have corrupt bitmap, we won't find any
* free blocks even though group info says we
* have free blocks
*/
ext4_grp_locked_error(sb, e4b->bd_group, 0, 0,
"%d free clusters as per "
"group info. But bitmap says 0",
free);
ext4_mark_group_bitmap_corrupted(sb, e4b->bd_group,
EXT4_GROUP_INFO_BBITMAP_CORRUPT);
break;
}
mb_find_extent(e4b, i, ac->ac_g_ex.fe_len, &ex);
if (WARN_ON(ex.fe_len <= 0))
break;
if (free < ex.fe_len) {
ext4_grp_locked_error(sb, e4b->bd_group, 0, 0,
"%d free clusters as per "
"group info. But got %d blocks",
free, ex.fe_len);
ext4_mark_group_bitmap_corrupted(sb, e4b->bd_group,
EXT4_GROUP_INFO_BBITMAP_CORRUPT);
/*
* The number of free blocks differs. This mostly
* indicate that the bitmap is corrupt. So exit
* without claiming the space.
*/
break;
}
ex.fe_logical = 0xDEADC0DE; /* debug value */
ext4_mb_measure_extent(ac, &ex, e4b);
i += ex.fe_len;
free -= ex.fe_len;
}
ext4_mb_check_limits(ac, e4b, 1);
}
/*
* This is a special case for storages like raid5
* we try to find stripe-aligned chunks for stripe-size-multiple requests
*/
static noinline_for_stack
void ext4_mb_scan_aligned(struct ext4_allocation_context *ac,
struct ext4_buddy *e4b)
{
struct super_block *sb = ac->ac_sb;
struct ext4_sb_info *sbi = EXT4_SB(sb);
void *bitmap = e4b->bd_bitmap;
struct ext4_free_extent ex;
ext4_fsblk_t first_group_block;
ext4_fsblk_t a;
ext4_grpblk_t i;
int max;
BUG_ON(sbi->s_stripe == 0);
/* find first stripe-aligned block in group */
first_group_block = ext4_group_first_block_no(sb, e4b->bd_group);
a = first_group_block + sbi->s_stripe - 1;
do_div(a, sbi->s_stripe);
i = (a * sbi->s_stripe) - first_group_block;
while (i < EXT4_CLUSTERS_PER_GROUP(sb)) {
if (!mb_test_bit(i, bitmap)) {
max = mb_find_extent(e4b, i, sbi->s_stripe, &ex);
if (max >= sbi->s_stripe) {
ac->ac_found++;
ex.fe_logical = 0xDEADF00D; /* debug value */
ac->ac_b_ex = ex;
ext4_mb_use_best_found(ac, e4b);
break;
}
}
i += sbi->s_stripe;
}
}
/*
* This is also called BEFORE we load the buddy bitmap.
* Returns either 1 or 0 indicating that the group is either suitable
* for the allocation or not.
*/
static bool ext4_mb_good_group(struct ext4_allocation_context *ac,
ext4_group_t group, int cr)
{
ext4_grpblk_t free, fragments;
int flex_size = ext4_flex_bg_size(EXT4_SB(ac->ac_sb));
struct ext4_group_info *grp = ext4_get_group_info(ac->ac_sb, group);
BUG_ON(cr < 0 || cr >= 4);
if (unlikely(EXT4_MB_GRP_BBITMAP_CORRUPT(grp)))
return false;
free = grp->bb_free;
if (free == 0)
return false;
fragments = grp->bb_fragments;
if (fragments == 0)
return false;
switch (cr) {
case 0:
BUG_ON(ac->ac_2order == 0);
/* Avoid using the first bg of a flexgroup for data files */
if ((ac->ac_flags & EXT4_MB_HINT_DATA) &&
(flex_size >= EXT4_FLEX_SIZE_DIR_ALLOC_SCHEME) &&
((group % flex_size) == 0))
return false;
if (free < ac->ac_g_ex.fe_len)
return false;
if (ac->ac_2order >= MB_NUM_ORDERS(ac->ac_sb))
return true;
if (grp->bb_largest_free_order < ac->ac_2order)
return false;
return true;
case 1:
if ((free / fragments) >= ac->ac_g_ex.fe_len)
return true;
break;
case 2:
if (free >= ac->ac_g_ex.fe_len)
return true;
break;
case 3:
return true;
default:
BUG();
}
return false;
}
/*
* This could return negative error code if something goes wrong
* during ext4_mb_init_group(). This should not be called with
* ext4_lock_group() held.
*
* Note: because we are conditionally operating with the group lock in
* the EXT4_MB_STRICT_CHECK case, we need to fake out sparse in this
* function using __acquire and __release. This means we need to be
* super careful before messing with the error path handling via "goto
* out"!
*/
static int ext4_mb_good_group_nolock(struct ext4_allocation_context *ac,
ext4_group_t group, int cr)
{
struct ext4_group_info *grp = ext4_get_group_info(ac->ac_sb, group);
struct super_block *sb = ac->ac_sb;
struct ext4_sb_info *sbi = EXT4_SB(sb);
bool should_lock = ac->ac_flags & EXT4_MB_STRICT_CHECK;
ext4_grpblk_t free;
int ret = 0;
if (sbi->s_mb_stats)
atomic64_inc(&sbi->s_bal_cX_groups_considered[ac->ac_criteria]);
if (should_lock) {
ext4_lock_group(sb, group);
__release(ext4_group_lock_ptr(sb, group));
}
free = grp->bb_free;
if (free == 0)
goto out;
if (cr <= 2 && free < ac->ac_g_ex.fe_len)
goto out;
if (unlikely(EXT4_MB_GRP_BBITMAP_CORRUPT(grp)))
goto out;
if (should_lock) {
__acquire(ext4_group_lock_ptr(sb, group));
ext4_unlock_group(sb, group);
}
/* We only do this if the grp has never been initialized */
if (unlikely(EXT4_MB_GRP_NEED_INIT(grp))) {
struct ext4_group_desc *gdp =
ext4_get_group_desc(sb, group, NULL);
int ret;
/* cr=0/1 is a very optimistic search to find large
* good chunks almost for free. If buddy data is not
* ready, then this optimization makes no sense. But
* we never skip the first block group in a flex_bg,
* since this gets used for metadata block allocation,
* and we want to make sure we locate metadata blocks
* in the first block group in the flex_bg if possible.
*/
if (cr < 2 &&
(!sbi->s_log_groups_per_flex ||
((group & ((1 << sbi->s_log_groups_per_flex) - 1)) != 0)) &&
!(ext4_has_group_desc_csum(sb) &&
(gdp->bg_flags & cpu_to_le16(EXT4_BG_BLOCK_UNINIT))))
return 0;
ret = ext4_mb_init_group(sb, group, GFP_NOFS);
if (ret)
return ret;
}
if (should_lock) {
ext4_lock_group(sb, group);
__release(ext4_group_lock_ptr(sb, group));
}
ret = ext4_mb_good_group(ac, group, cr);
out:
if (should_lock) {
__acquire(ext4_group_lock_ptr(sb, group));
ext4_unlock_group(sb, group);
}
return ret;
}
/*
* Start prefetching @nr block bitmaps starting at @group.
* Return the next group which needs to be prefetched.
*/
ext4_group_t ext4_mb_prefetch(struct super_block *sb, ext4_group_t group,
unsigned int nr, int *cnt)
{
ext4_group_t ngroups = ext4_get_groups_count(sb);
struct buffer_head *bh;
struct blk_plug plug;
blk_start_plug(&plug);
while (nr-- > 0) {
struct ext4_group_desc *gdp = ext4_get_group_desc(sb, group,
NULL);
struct ext4_group_info *grp = ext4_get_group_info(sb, group);
/*
* Prefetch block groups with free blocks; but don't
* bother if it is marked uninitialized on disk, since
* it won't require I/O to read. Also only try to
* prefetch once, so we avoid getblk() call, which can
* be expensive.
*/
if (!EXT4_MB_GRP_TEST_AND_SET_READ(grp) &&
EXT4_MB_GRP_NEED_INIT(grp) &&
ext4_free_group_clusters(sb, gdp) > 0 &&
!(ext4_has_group_desc_csum(sb) &&
(gdp->bg_flags & cpu_to_le16(EXT4_BG_BLOCK_UNINIT)))) {
bh = ext4_read_block_bitmap_nowait(sb, group, true);
if (bh && !IS_ERR(bh)) {
if (!buffer_uptodate(bh) && cnt)
(*cnt)++;
brelse(bh);
}
}
if (++group >= ngroups)
group = 0;
}
blk_finish_plug(&plug);
return group;
}
/*
* Prefetching reads the block bitmap into the buffer cache; but we
* need to make sure that the buddy bitmap in the page cache has been
* initialized. Note that ext4_mb_init_group() will block if the I/O
* is not yet completed, or indeed if it was not initiated by
* ext4_mb_prefetch did not start the I/O.
*
* TODO: We should actually kick off the buddy bitmap setup in a work
* queue when the buffer I/O is completed, so that we don't block
* waiting for the block allocation bitmap read to finish when
* ext4_mb_prefetch_fini is called from ext4_mb_regular_allocator().
*/
void ext4_mb_prefetch_fini(struct super_block *sb, ext4_group_t group,
unsigned int nr)
{
while (nr-- > 0) {
struct ext4_group_desc *gdp = ext4_get_group_desc(sb, group,
NULL);
struct ext4_group_info *grp = ext4_get_group_info(sb, group);
if (!group)
group = ext4_get_groups_count(sb);
group--;
grp = ext4_get_group_info(sb, group);
if (EXT4_MB_GRP_NEED_INIT(grp) &&
ext4_free_group_clusters(sb, gdp) > 0 &&
!(ext4_has_group_desc_csum(sb) &&
(gdp->bg_flags & cpu_to_le16(EXT4_BG_BLOCK_UNINIT)))) {
if (ext4_mb_init_group(sb, group, GFP_NOFS))
break;
}
}
}
static noinline_for_stack int
ext4_mb_regular_allocator(struct ext4_allocation_context *ac)
{
ext4_group_t prefetch_grp = 0, ngroups, group, i;
int cr = -1;
int err = 0, first_err = 0;
unsigned int nr = 0, prefetch_ios = 0;
struct ext4_sb_info *sbi;
struct super_block *sb;
struct ext4_buddy e4b;
int lost;
sb = ac->ac_sb;
sbi = EXT4_SB(sb);
ngroups = ext4_get_groups_count(sb);
/* non-extent files are limited to low blocks/groups */
if (!(ext4_test_inode_flag(ac->ac_inode, EXT4_INODE_EXTENTS)))
ngroups = sbi->s_blockfile_groups;
BUG_ON(ac->ac_status == AC_STATUS_FOUND);
/* first, try the goal */
err = ext4_mb_find_by_goal(ac, &e4b);
if (err || ac->ac_status == AC_STATUS_FOUND)
goto out;
if (unlikely(ac->ac_flags & EXT4_MB_HINT_GOAL_ONLY))
goto out;
/*
* ac->ac_2order is set only if the fe_len is a power of 2
* if ac->ac_2order is set we also set criteria to 0 so that we
* try exact allocation using buddy.
*/
i = fls(ac->ac_g_ex.fe_len);
ac->ac_2order = 0;
/*
* We search using buddy data only if the order of the request
* is greater than equal to the sbi_s_mb_order2_reqs
* You can tune it via /sys/fs/ext4/<partition>/mb_order2_req
* We also support searching for power-of-two requests only for
* requests upto maximum buddy size we have constructed.
*/
if (i >= sbi->s_mb_order2_reqs && i <= MB_NUM_ORDERS(sb)) {
/*
* This should tell if fe_len is exactly power of 2
*/
if ((ac->ac_g_ex.fe_len & (~(1 << (i - 1)))) == 0)
ac->ac_2order = array_index_nospec(i - 1,
MB_NUM_ORDERS(sb));
}
/* if stream allocation is enabled, use global goal */
if (ac->ac_flags & EXT4_MB_STREAM_ALLOC) {
/* TBD: may be hot point */
spin_lock(&sbi->s_md_lock);
ac->ac_g_ex.fe_group = sbi->s_mb_last_group;
ac->ac_g_ex.fe_start = sbi->s_mb_last_start;
spin_unlock(&sbi->s_md_lock);
}
/* Let's just scan groups to find more-less suitable blocks */
cr = ac->ac_2order ? 0 : 1;
/*
* cr == 0 try to get exact allocation,
* cr == 3 try to get anything
*/
repeat:
for (; cr < 4 && ac->ac_status == AC_STATUS_CONTINUE; cr++) {
ac->ac_criteria = cr;
/*
* searching for the right group start
* from the goal value specified
*/
group = ac->ac_g_ex.fe_group;
ac->ac_last_optimal_group = group;
ac->ac_groups_linear_remaining = sbi->s_mb_max_linear_groups;
prefetch_grp = group;
for (i = 0; i < ngroups; group = next_linear_group(ac, group, ngroups),
i++) {
int ret = 0, new_cr;
cond_resched();
ext4_mb_choose_next_group(ac, &new_cr, &group, ngroups);
if (new_cr != cr) {
cr = new_cr;
goto repeat;
}
/*
* Batch reads of the block allocation bitmaps
* to get multiple READs in flight; limit
* prefetching at cr=0/1, otherwise mballoc can
* spend a lot of time loading imperfect groups
*/
if ((prefetch_grp == group) &&
(cr > 1 ||
prefetch_ios < sbi->s_mb_prefetch_limit)) {
unsigned int curr_ios = prefetch_ios;
nr = sbi->s_mb_prefetch;
if (ext4_has_feature_flex_bg(sb)) {
nr = 1 << sbi->s_log_groups_per_flex;
nr -= group & (nr - 1);
nr = min(nr, sbi->s_mb_prefetch);
}
prefetch_grp = ext4_mb_prefetch(sb, group,
nr, &prefetch_ios);
if (prefetch_ios == curr_ios)
nr = 0;
}
/* This now checks without needing the buddy page */
ret = ext4_mb_good_group_nolock(ac, group, cr);
if (ret <= 0) {
if (!first_err)
first_err = ret;
continue;
}
err = ext4_mb_load_buddy(sb, group, &e4b);
if (err)
goto out;
ext4_lock_group(sb, group);
/*
* We need to check again after locking the
* block group
*/
ret = ext4_mb_good_group(ac, group, cr);
if (ret == 0) {
ext4_unlock_group(sb, group);
ext4_mb_unload_buddy(&e4b);
continue;
}
ac->ac_groups_scanned++;
if (cr == 0)
ext4_mb_simple_scan_group(ac, &e4b);
else if (cr == 1 && sbi->s_stripe &&
!(ac->ac_g_ex.fe_len % sbi->s_stripe))
ext4_mb_scan_aligned(ac, &e4b);
else
ext4_mb_complex_scan_group(ac, &e4b);
ext4_unlock_group(sb, group);
ext4_mb_unload_buddy(&e4b);
if (ac->ac_status != AC_STATUS_CONTINUE)
break;
}
/* Processed all groups and haven't found blocks */
if (sbi->s_mb_stats && i == ngroups)
atomic64_inc(&sbi->s_bal_cX_failed[cr]);
}
if (ac->ac_b_ex.fe_len > 0 && ac->ac_status != AC_STATUS_FOUND &&
!(ac->ac_flags & EXT4_MB_HINT_FIRST)) {
/*
* We've been searching too long. Let's try to allocate
* the best chunk we've found so far
*/
ext4_mb_try_best_found(ac, &e4b);
if (ac->ac_status != AC_STATUS_FOUND) {
/*
* Someone more lucky has already allocated it.
* The only thing we can do is just take first
* found block(s)
*/
lost = atomic_inc_return(&sbi->s_mb_lost_chunks);
mb_debug(sb, "lost chunk, group: %u, start: %d, len: %d, lost: %d\n",
ac->ac_b_ex.fe_group, ac->ac_b_ex.fe_start,
ac->ac_b_ex.fe_len, lost);
ac->ac_b_ex.fe_group = 0;
ac->ac_b_ex.fe_start = 0;
ac->ac_b_ex.fe_len = 0;
ac->ac_status = AC_STATUS_CONTINUE;
ac->ac_flags |= EXT4_MB_HINT_FIRST;
cr = 3;
goto repeat;
}
}
if (sbi->s_mb_stats && ac->ac_status == AC_STATUS_FOUND)
atomic64_inc(&sbi->s_bal_cX_hits[ac->ac_criteria]);
out:
if (!err && ac->ac_status != AC_STATUS_FOUND && first_err)
err = first_err;
mb_debug(sb, "Best len %d, origin len %d, ac_status %u, ac_flags 0x%x, cr %d ret %d\n",
ac->ac_b_ex.fe_len, ac->ac_o_ex.fe_len, ac->ac_status,
ac->ac_flags, cr, err);
if (nr)
ext4_mb_prefetch_fini(sb, prefetch_grp, nr);
return err;
}
static void *ext4_mb_seq_groups_start(struct seq_file *seq, loff_t *pos)
{
struct super_block *sb = PDE_DATA(file_inode(seq->file));
ext4_group_t group;
if (*pos < 0 || *pos >= ext4_get_groups_count(sb))
return NULL;
group = *pos + 1;
return (void *) ((unsigned long) group);
}
static void *ext4_mb_seq_groups_next(struct seq_file *seq, void *v, loff_t *pos)
{
struct super_block *sb = PDE_DATA(file_inode(seq->file));
ext4_group_t group;
++*pos;
if (*pos < 0 || *pos >= ext4_get_groups_count(sb))
return NULL;
group = *pos + 1;
return (void *) ((unsigned long) group);
}
static int ext4_mb_seq_groups_show(struct seq_file *seq, void *v)
{
struct super_block *sb = PDE_DATA(file_inode(seq->file));
ext4_group_t group = (ext4_group_t) ((unsigned long) v);
int i;
int err, buddy_loaded = 0;
struct ext4_buddy e4b;
struct ext4_group_info *grinfo;
unsigned char blocksize_bits = min_t(unsigned char,
sb->s_blocksize_bits,
EXT4_MAX_BLOCK_LOG_SIZE);
struct sg {
struct ext4_group_info info;
ext4_grpblk_t counters[EXT4_MAX_BLOCK_LOG_SIZE + 2];
} sg;
group--;
if (group == 0)
seq_puts(seq, "#group: free frags first ["
" 2^0 2^1 2^2 2^3 2^4 2^5 2^6 "
" 2^7 2^8 2^9 2^10 2^11 2^12 2^13 ]\n");
i = (blocksize_bits + 2) * sizeof(sg.info.bb_counters[0]) +
sizeof(struct ext4_group_info);
grinfo = ext4_get_group_info(sb, group);
/* Load the group info in memory only if not already loaded. */
if (unlikely(EXT4_MB_GRP_NEED_INIT(grinfo))) {
err = ext4_mb_load_buddy(sb, group, &e4b);
if (err) {
seq_printf(seq, "#%-5u: I/O error\n", group);
return 0;
}
buddy_loaded = 1;
}
memcpy(&sg, ext4_get_group_info(sb, group), i);
if (buddy_loaded)
ext4_mb_unload_buddy(&e4b);
seq_printf(seq, "#%-5u: %-5u %-5u %-5u [", group, sg.info.bb_free,
sg.info.bb_fragments, sg.info.bb_first_free);
for (i = 0; i <= 13; i++)
seq_printf(seq, " %-5u", i <= blocksize_bits + 1 ?
sg.info.bb_counters[i] : 0);
seq_puts(seq, " ]\n");
return 0;
}
static void ext4_mb_seq_groups_stop(struct seq_file *seq, void *v)
{
}
const struct seq_operations ext4_mb_seq_groups_ops = {
.start = ext4_mb_seq_groups_start,
.next = ext4_mb_seq_groups_next,
.stop = ext4_mb_seq_groups_stop,
.show = ext4_mb_seq_groups_show,
};
int ext4_seq_mb_stats_show(struct seq_file *seq, void *offset)
{
struct super_block *sb = (struct super_block *)seq->private;
struct ext4_sb_info *sbi = EXT4_SB(sb);
seq_puts(seq, "mballoc:\n");
if (!sbi->s_mb_stats) {
seq_puts(seq, "\tmb stats collection turned off.\n");
seq_puts(seq, "\tTo enable, please write \"1\" to sysfs file mb_stats.\n");
return 0;
}
seq_printf(seq, "\treqs: %u\n", atomic_read(&sbi->s_bal_reqs));
seq_printf(seq, "\tsuccess: %u\n", atomic_read(&sbi->s_bal_success));
seq_printf(seq, "\tgroups_scanned: %u\n", atomic_read(&sbi->s_bal_groups_scanned));
seq_puts(seq, "\tcr0_stats:\n");
seq_printf(seq, "\t\thits: %llu\n", atomic64_read(&sbi->s_bal_cX_hits[0]));
seq_printf(seq, "\t\tgroups_considered: %llu\n",
atomic64_read(&sbi->s_bal_cX_groups_considered[0]));
seq_printf(seq, "\t\tuseless_loops: %llu\n",
atomic64_read(&sbi->s_bal_cX_failed[0]));
seq_printf(seq, "\t\tbad_suggestions: %u\n",
atomic_read(&sbi->s_bal_cr0_bad_suggestions));
seq_puts(seq, "\tcr1_stats:\n");
seq_printf(seq, "\t\thits: %llu\n", atomic64_read(&sbi->s_bal_cX_hits[1]));
seq_printf(seq, "\t\tgroups_considered: %llu\n",
atomic64_read(&sbi->s_bal_cX_groups_considered[1]));
seq_printf(seq, "\t\tuseless_loops: %llu\n",
atomic64_read(&sbi->s_bal_cX_failed[1]));
seq_printf(seq, "\t\tbad_suggestions: %u\n",
atomic_read(&sbi->s_bal_cr1_bad_suggestions));
seq_puts(seq, "\tcr2_stats:\n");
seq_printf(seq, "\t\thits: %llu\n", atomic64_read(&sbi->s_bal_cX_hits[2]));
seq_printf(seq, "\t\tgroups_considered: %llu\n",
atomic64_read(&sbi->s_bal_cX_groups_considered[2]));
seq_printf(seq, "\t\tuseless_loops: %llu\n",
atomic64_read(&sbi->s_bal_cX_failed[2]));
seq_puts(seq, "\tcr3_stats:\n");
seq_printf(seq, "\t\thits: %llu\n", atomic64_read(&sbi->s_bal_cX_hits[3]));
seq_printf(seq, "\t\tgroups_considered: %llu\n",
atomic64_read(&sbi->s_bal_cX_groups_considered[3]));
seq_printf(seq, "\t\tuseless_loops: %llu\n",
atomic64_read(&sbi->s_bal_cX_failed[3]));
seq_printf(seq, "\textents_scanned: %u\n", atomic_read(&sbi->s_bal_ex_scanned));
seq_printf(seq, "\t\tgoal_hits: %u\n", atomic_read(&sbi->s_bal_goals));
seq_printf(seq, "\t\t2^n_hits: %u\n", atomic_read(&sbi->s_bal_2orders));
seq_printf(seq, "\t\tbreaks: %u\n", atomic_read(&sbi->s_bal_breaks));
seq_printf(seq, "\t\tlost: %u\n", atomic_read(&sbi->s_mb_lost_chunks));
seq_printf(seq, "\tbuddies_generated: %u/%u\n",
atomic_read(&sbi->s_mb_buddies_generated),
ext4_get_groups_count(sb));
seq_printf(seq, "\tbuddies_time_used: %llu\n",
atomic64_read(&sbi->s_mb_generation_time));
seq_printf(seq, "\tpreallocated: %u\n",
atomic_read(&sbi->s_mb_preallocated));
seq_printf(seq, "\tdiscarded: %u\n",
atomic_read(&sbi->s_mb_discarded));
return 0;
}
static void *ext4_mb_seq_structs_summary_start(struct seq_file *seq, loff_t *pos)
__acquires(&EXT4_SB(sb)->s_mb_rb_lock)
{
struct super_block *sb = PDE_DATA(file_inode(seq->file));
unsigned long position;
read_lock(&EXT4_SB(sb)->s_mb_rb_lock);
if (*pos < 0 || *pos >= MB_NUM_ORDERS(sb) + 1)
return NULL;
position = *pos + 1;
return (void *) ((unsigned long) position);
}
static void *ext4_mb_seq_structs_summary_next(struct seq_file *seq, void *v, loff_t *pos)
{
struct super_block *sb = PDE_DATA(file_inode(seq->file));
unsigned long position;
++*pos;
if (*pos < 0 || *pos >= MB_NUM_ORDERS(sb) + 1)
return NULL;
position = *pos + 1;
return (void *) ((unsigned long) position);
}
static int ext4_mb_seq_structs_summary_show(struct seq_file *seq, void *v)
{
struct super_block *sb = PDE_DATA(file_inode(seq->file));
struct ext4_sb_info *sbi = EXT4_SB(sb);
unsigned long position = ((unsigned long) v);
struct ext4_group_info *grp;
struct rb_node *n;
unsigned int count, min, max;
position--;
if (position >= MB_NUM_ORDERS(sb)) {
seq_puts(seq, "fragment_size_tree:\n");
n = rb_first(&sbi->s_mb_avg_fragment_size_root);
if (!n) {
seq_puts(seq, "\ttree_min: 0\n\ttree_max: 0\n\ttree_nodes: 0\n");
return 0;
}
grp = rb_entry(n, struct ext4_group_info, bb_avg_fragment_size_rb);
min = grp->bb_fragments ? grp->bb_free / grp->bb_fragments : 0;
count = 1;
while (rb_next(n)) {
count++;
n = rb_next(n);
}
grp = rb_entry(n, struct ext4_group_info, bb_avg_fragment_size_rb);
max = grp->bb_fragments ? grp->bb_free / grp->bb_fragments : 0;
seq_printf(seq, "\ttree_min: %u\n\ttree_max: %u\n\ttree_nodes: %u\n",
min, max, count);
return 0;
}
if (position == 0) {
seq_printf(seq, "optimize_scan: %d\n",
test_opt2(sb, MB_OPTIMIZE_SCAN) ? 1 : 0);
seq_puts(seq, "max_free_order_lists:\n");
}
count = 0;
list_for_each_entry(grp, &sbi->s_mb_largest_free_orders[position],
bb_largest_free_order_node)
count++;
seq_printf(seq, "\tlist_order_%u_groups: %u\n",
(unsigned int)position, count);
return 0;
}
static void ext4_mb_seq_structs_summary_stop(struct seq_file *seq, void *v)
__releases(&EXT4_SB(sb)->s_mb_rb_lock)
{
struct super_block *sb = PDE_DATA(file_inode(seq->file));
read_unlock(&EXT4_SB(sb)->s_mb_rb_lock);
}
const struct seq_operations ext4_mb_seq_structs_summary_ops = {
.start = ext4_mb_seq_structs_summary_start,
.next = ext4_mb_seq_structs_summary_next,
.stop = ext4_mb_seq_structs_summary_stop,
.show = ext4_mb_seq_structs_summary_show,
};
static struct kmem_cache *get_groupinfo_cache(int blocksize_bits)
{
int cache_index = blocksize_bits - EXT4_MIN_BLOCK_LOG_SIZE;
struct kmem_cache *cachep = ext4_groupinfo_caches[cache_index];