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Merge branch 'for-4.10/fs-unmap' of git://git.kernel.dk/linux-block

Browse source 
Pull fs meta data unmap optimization from Jens Axboe:
 "A series from Jan Kara, providing a more efficient way for unmapping
  meta data from in the buffer cache than doing it block-by-block.

  Provide a general helper that existing callers can use"

* 'for-4.10/fs-unmap' of git://git.kernel.dk/linux-block:
  fs: Remove unmap_underlying_metadata
  fs: Add helper to clean bdev aliases under a bh and use it
  ext2: Use clean_bdev_aliases() instead of iteration
  ext4: Use clean_bdev_aliases() instead of iteration
  direct-io: Use clean_bdev_aliases() instead of handmade iteration
  fs: Provide function to unmap metadata for a range of blocks
This commit is contained in:
Linus Torvalds 2016-12-14 17:09:00 -08:00
commit 80eabba702
13 changed files with 102 additions and 93 deletions
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100
fs/buffer.c
View file

@ -43,6 +43,7 @@
#include <linux/bitops.h>
#include <linux/mpage.h>
#include <linux/bit_spinlock.h>
#include <linux/pagevec.h>
#include <trace/events/block.h>
static int fsync_buffers_list(spinlock_t *lock, struct list_head *list);
@ -1604,37 +1605,80 @@ void create_empty_buffers(struct page *page,
}
EXPORT_SYMBOL(create_empty_buffers);
/*
* We are taking a block for data and we don't want any output from any
* buffer-cache aliases starting from return from that function and
* until the moment when something will explicitly mark the buffer
* dirty (hopefully that will not happen until we will free that block ;-)
* We don't even need to mark it not-uptodate - nobody can expect
* anything from a newly allocated buffer anyway. We used to used
* unmap_buffer() for such invalidation, but that was wrong. We definitely
* don't want to mark the alias unmapped, for example - it would confuse
* anyone who might pick it with bread() afterwards...
/**
* clean_bdev_aliases: clean a range of buffers in block device
* @bdev: Block device to clean buffers in
* @block: Start of a range of blocks to clean
* @len: Number of blocks to clean
*
* Also.. Note that bforget() doesn't lock the buffer. So there can
* be writeout I/O going on against recently-freed buffers. We don't
* wait on that I/O in bforget() - it's more efficient to wait on the I/O
* only if we really need to. That happens here.
* We are taking a range of blocks for data and we don't want writeback of any
* buffer-cache aliases starting from return from this function and until the
* moment when something will explicitly mark the buffer dirty (hopefully that
* will not happen until we will free that block ;-) We don't even need to mark
* it not-uptodate - nobody can expect anything from a newly allocated buffer
* anyway. We used to use unmap_buffer() for such invalidation, but that was
* wrong. We definitely don't want to mark the alias unmapped, for example - it
* would confuse anyone who might pick it with bread() afterwards...
*
* Also.. Note that bforget() doesn't lock the buffer. So there can be
* writeout I/O going on against recently-freed buffers. We don't wait on that
* I/O in bforget() - it's more efficient to wait on the I/O only if we really
* need to. That happens here.
*/
void unmap_underlying_metadata(struct block_device *bdev, sector_t block)
void clean_bdev_aliases(struct block_device *bdev, sector_t block, sector_t len)
{
struct buffer_head *old_bh;
struct inode *bd_inode = bdev->bd_inode;
struct address_space *bd_mapping = bd_inode->i_mapping;
struct pagevec pvec;
pgoff_t index = block >> (PAGE_SHIFT - bd_inode->i_blkbits);
pgoff_t end;
int i;
struct buffer_head *bh;
struct buffer_head *head;
might_sleep();
end = (block + len - 1) >> (PAGE_SHIFT - bd_inode->i_blkbits);
pagevec_init(&pvec, 0);
while (index <= end && pagevec_lookup(&pvec, bd_mapping, index,
min(end - index, (pgoff_t)PAGEVEC_SIZE - 1) + 1)) {
for (i = 0; i < pagevec_count(&pvec); i++) {
struct page *page = pvec.pages[i];
old_bh = __find_get_block_slow(bdev, block);
if (old_bh) {
clear_buffer_dirty(old_bh);
wait_on_buffer(old_bh);
clear_buffer_req(old_bh);
__brelse(old_bh);
index = page->index;
if (index > end)
break;
if (!page_has_buffers(page))
continue;
/*
* We use page lock instead of bd_mapping->private_lock
* to pin buffers here since we can afford to sleep and
* it scales better than a global spinlock lock.
*/
lock_page(page);
/* Recheck when the page is locked which pins bhs */
if (!page_has_buffers(page))
goto unlock_page;
head = page_buffers(page);
bh = head;
do {
if (!buffer_mapped(bh))
goto next;
if (bh->b_blocknr >= block + len)
break;
clear_buffer_dirty(bh);
wait_on_buffer(bh);
clear_buffer_req(bh);
next:
bh = bh->b_this_page;
} while (bh != head);
unlock_page:
unlock_page(page);
}
pagevec_release(&pvec);
cond_resched();
index++;
}
}
EXPORT_SYMBOL(unmap_underlying_metadata);
EXPORT_SYMBOL(clean_bdev_aliases);
/*
* Size is a power-of-two in the range 512..PAGE_SIZE,
@ -1745,8 +1789,7 @@ int __block_write_full_page(struct inode *inode, struct page *page,
if (buffer_new(bh)) {
/* blockdev mappings never come here */
clear_buffer_new(bh);
unmap_underlying_metadata(bh->b_bdev,
bh->b_blocknr);
clean_bdev_bh_alias(bh);
}
}
bh = bh->b_this_page;
@ -1992,8 +2035,7 @@ int __block_write_begin_int(struct page *page, loff_t pos, unsigned len,
}
if (buffer_new(bh)) {
unmap_underlying_metadata(bh->b_bdev,
bh->b_blocknr);
clean_bdev_bh_alias(bh);
if (PageUptodate(page)) {
clear_buffer_new(bh);
set_buffer_uptodate(bh);
@ -2633,7 +2675,7 @@ int nobh_write_begin(struct address_space *mapping,
if (!buffer_mapped(bh))
is_mapped_to_disk = 0;
if (buffer_new(bh))
unmap_underlying_metadata(bh->b_bdev, bh->b_blocknr);
clean_bdev_bh_alias(bh);
if (PageUptodate(page)) {
set_buffer_uptodate(bh);
continue;