Commit d2eecb03 authored by Theodore Ts'o's avatar Theodore Ts'o

ext4: Use slab allocator for sub-page sized allocations

Now that the SLUB seems to be fixed so that it respects the requested
alignment, use kmem_cache_alloc() to allocator if the block size of
the buffer heads to be allocated is less than the page size.
Previously, we were using 16k page on a Power system for each buffer,
even when the file system was using 1k or 4k block size.
Signed-off-by: default avatar"Theodore Ts'o" <tytso@mit.edu>
parent f8ec9d68
......@@ -39,6 +39,8 @@
#include <linux/seq_file.h>
#include <linux/math64.h>
#include <linux/hash.h>
#include <linux/log2.h>
#include <linux/vmalloc.h>
#define CREATE_TRACE_POINTS
#include <trace/events/jbd2.h>
......@@ -93,6 +95,7 @@ EXPORT_SYMBOL(jbd2_journal_begin_ordered_truncate);
static int journal_convert_superblock_v1(journal_t *, journal_superblock_t *);
static void __journal_abort_soft (journal_t *journal, int errno);
static int jbd2_journal_create_slab(size_t slab_size);
/*
* Helper function used to manage commit timeouts
......@@ -1248,6 +1251,13 @@ int jbd2_journal_load(journal_t *journal)
}
}
/*
* Create a slab for this blocksize
*/
err = jbd2_journal_create_slab(be32_to_cpu(sb->s_blocksize));
if (err)
return err;
/* Let the recovery code check whether it needs to recover any
* data from the journal. */
if (jbd2_journal_recover(journal))
......@@ -1806,6 +1816,127 @@ size_t journal_tag_bytes(journal_t *journal)
return JBD2_TAG_SIZE32;
}
/*
* JBD memory management
*
* These functions are used to allocate block-sized chunks of memory
* used for making copies of buffer_head data. Very often it will be
* page-sized chunks of data, but sometimes it will be in
* sub-page-size chunks. (For example, 16k pages on Power systems
* with a 4k block file system.) For blocks smaller than a page, we
* use a SLAB allocator. There are slab caches for each block size,
* which are allocated at mount time, if necessary, and we only free
* (all of) the slab caches when/if the jbd2 module is unloaded. For
* this reason we don't need to a mutex to protect access to
* jbd2_slab[] allocating or releasing memory; only in
* jbd2_journal_create_slab().
*/
#define JBD2_MAX_SLABS 8
static struct kmem_cache *jbd2_slab[JBD2_MAX_SLABS];
static DECLARE_MUTEX(jbd2_slab_create_sem);
static const char *jbd2_slab_names[JBD2_MAX_SLABS] = {
"jbd2_1k", "jbd2_2k", "jbd2_4k", "jbd2_8k",
"jbd2_16k", "jbd2_32k", "jbd2_64k", "jbd2_128k"
};
static void jbd2_journal_destroy_slabs(void)
{
int i;
for (i = 0; i < JBD2_MAX_SLABS; i++) {
if (jbd2_slab[i])
kmem_cache_destroy(jbd2_slab[i]);
jbd2_slab[i] = NULL;
}
}
static int jbd2_journal_create_slab(size_t size)
{
int i = order_base_2(size) - 10;
size_t slab_size;
if (size == PAGE_SIZE)
return 0;
if (i >= JBD2_MAX_SLABS)
return -EINVAL;
if (unlikely(i < 0))
i = 0;
down(&jbd2_slab_create_sem);
if (jbd2_slab[i]) {
up(&jbd2_slab_create_sem);
return 0; /* Already created */
}
slab_size = 1 << (i+10);
jbd2_slab[i] = kmem_cache_create(jbd2_slab_names[i], slab_size,
slab_size, 0, NULL);
up(&jbd2_slab_create_sem);
if (!jbd2_slab[i]) {
printk(KERN_EMERG "JBD2: no memory for jbd2_slab cache\n");
return -ENOMEM;
}
return 0;
}
static struct kmem_cache *get_slab(size_t size)
{
int i = order_base_2(size) - 10;
BUG_ON(i >= JBD2_MAX_SLABS);
if (unlikely(i < 0))
i = 0;
BUG_ON(jbd2_slab[i] == 0);
return jbd2_slab[i];
}
void *jbd2_alloc(size_t size, gfp_t flags)
{
void *ptr;
BUG_ON(size & (size-1)); /* Must be a power of 2 */
flags |= __GFP_REPEAT;
if (size == PAGE_SIZE)
ptr = (void *)__get_free_pages(flags, 0);
else if (size > PAGE_SIZE) {
int order = get_order(size);
if (order < 3)
ptr = (void *)__get_free_pages(flags, order);
else
ptr = vmalloc(size);
} else
ptr = kmem_cache_alloc(get_slab(size), flags);
/* Check alignment; SLUB has gotten this wrong in the past,
* and this can lead to user data corruption! */
BUG_ON(((unsigned long) ptr) & (size-1));
return ptr;
}
void jbd2_free(void *ptr, size_t size)
{
if (size == PAGE_SIZE) {
free_pages((unsigned long)ptr, 0);
return;
}
if (size > PAGE_SIZE) {
int order = get_order(size);
if (order < 3)
free_pages((unsigned long)ptr, order);
else
vfree(ptr);
return;
}
kmem_cache_free(get_slab(size), ptr);
};
/*
* Journal_head storage management
*/
......@@ -2204,6 +2335,7 @@ static void jbd2_journal_destroy_caches(void)
jbd2_journal_destroy_revoke_caches();
jbd2_journal_destroy_jbd2_journal_head_cache();
jbd2_journal_destroy_handle_cache();
jbd2_journal_destroy_slabs();
}
static int __init journal_init(void)
......
......@@ -69,15 +69,8 @@ extern u8 jbd2_journal_enable_debug;
#define jbd_debug(f, a...) /**/
#endif
static inline void *jbd2_alloc(size_t size, gfp_t flags)
{
return (void *)__get_free_pages(flags, get_order(size));
}
static inline void jbd2_free(void *ptr, size_t size)
{
free_pages((unsigned long)ptr, get_order(size));
};
extern void *jbd2_alloc(size_t size, gfp_t flags);
extern void jbd2_free(void *ptr, size_t size);
#define JBD2_MIN_JOURNAL_BLOCKS 1024
......
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