Commit fa399c31 authored by Matthew Wilcox (Oracle)'s avatar Matthew Wilcox (Oracle) Committed by Andrew Morton
Browse files

buffer: fix more functions for block size > PAGE_SIZE 

Both __block_write_full_folio() and block_read_full_folio() assumed that
block size <= PAGE_SIZE.  Replace the shift with a divide, which is
probably cheaper than first calculating the shift.  That lets us remove
block_size_bits() as these were the last callers.

Link: https://lkml.kernel.org/r/20231109210608.2252323-8-willy@infradead.org


Signed-off-by: default avatarMatthew Wilcox (Oracle) <willy@infradead.org>
Cc: Hannes Reinecke <hare@suse.de>
Cc: Luis Chamberlain <mcgrof@kernel.org>
Cc: Pankaj Raghav <p.raghav@samsung.com>
Cc: Ryusuke Konishi <konishi.ryusuke@gmail.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent b0619401

fs/buffer.c

+6 −21
Original line number Diff line number Diff line
@@ -1742,19 +1742,6 @@ void clean_bdev_aliases(struct block_device *bdev, sector_t block, sector_t len) 
}

EXPORT_SYMBOL(clean_bdev_aliases);



/*

 * Size is a power-of-two in the range 512..PAGE_SIZE,

 * and the case we care about most is PAGE_SIZE.

 *

 * So this *could* possibly be written with those

 * constraints in mind (relevant mostly if some

 * architecture has a slow bit-scan instruction)

 */

static inline int block_size_bits(unsigned int blocksize)

{

	return ilog2(blocksize);

}



static struct buffer_head *folio_create_buffers(struct folio *folio,

						struct inode *inode,

						unsigned int b_state)
@@ -1807,7 +1794,7 @@ int __block_write_full_folio(struct inode *inode, struct folio *folio, 
	sector_t block;

	sector_t last_block;

	struct buffer_head *bh, *head;

	unsigned int blocksize, bbits;

	size_t blocksize;

	int nr_underway = 0;

	blk_opf_t write_flags = wbc_to_write_flags(wbc);
@@ -1826,10 +1813,9 @@ int __block_write_full_folio(struct inode *inode, struct folio *folio, 


	bh = head;

	blocksize = bh->b_size;

	bbits = block_size_bits(blocksize);



	block = (sector_t)folio->index << (PAGE_SHIFT - bbits);

	last_block = (i_size_read(inode) - 1) >> bbits;

	block = div_u64(folio_pos(folio), blocksize);

	last_block = div_u64(i_size_read(inode) - 1, blocksize);



	/*

	 * Get all the dirty buffers mapped to disk addresses and
@@ -2355,7 +2341,7 @@ int block_read_full_folio(struct folio *folio, get_block_t *get_block) 
	struct inode *inode = folio->mapping->host;

	sector_t iblock, lblock;

	struct buffer_head *bh, *head, *arr[MAX_BUF_PER_PAGE];

	unsigned int blocksize, bbits;

	size_t blocksize;

	int nr, i;

	int fully_mapped = 1;

	bool page_error = false;
@@ -2369,10 +2355,9 @@ int block_read_full_folio(struct folio *folio, get_block_t *get_block) 


	head = folio_create_buffers(folio, inode, 0);

	blocksize = head->b_size;

	bbits = block_size_bits(blocksize);



	iblock = (sector_t)folio->index << (PAGE_SHIFT - bbits);

	lblock = (limit+blocksize-1) >> bbits;

	iblock = div_u64(folio_pos(folio), blocksize);

	lblock = div_u64(limit + blocksize - 1, blocksize);

	bh = head;

	nr = 0;

	i = 0;