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fs: add CONFIG_BUFFER_HEAD

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Add a new config option that controls building the buffer_head code, and
select it from all file systems and stacking drivers that need it.

For the block device nodes and alternative iomap based buffered I/O path
is provided when buffer_head support is not enabled, and iomap needs a
a small tweak to define the IOMAP_F_BUFFER_HEAD flag to 0 to not call
into the buffer_head code when it doesn't exist.

Otherwise this is just Kconfig and ifdef changes.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Luis Chamberlain <mcgrof@kernel.org>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Link: https://lore.kernel.org/r/20230801172201.1923299-7-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Christoph Hellwig
2023-08-01 19:22:01 +02:00
committed by Jens Axboe
parent 487c607df7
commit 925c86a19b
37 changed files with 119 additions and 29 deletions
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70
block/fops.c
View File

@@ -24,15 +24,6 @@ static inline struct inode *bdev_file_inode(struct file *file)
return file->f_mapping->host;
}
static int blkdev_get_block(struct inode *inode, sector_t iblock,
struct buffer_head *bh, int create)
{
bh->b_bdev = I_BDEV(inode);
bh->b_blocknr = iblock;
set_buffer_mapped(bh);
return 0;
}
static blk_opf_t dio_bio_write_op(struct kiocb *iocb)
{
blk_opf_t opf = REQ_OP_WRITE | REQ_SYNC | REQ_IDLE;
@@ -400,7 +391,7 @@ static int blkdev_iomap_begin(struct inode *inode, loff_t offset, loff_t length,
iomap->type = IOMAP_MAPPED;
iomap->addr = iomap->offset;
iomap->length = isize - iomap->offset;
iomap->flags |= IOMAP_F_BUFFER_HEAD;
iomap->flags |= IOMAP_F_BUFFER_HEAD; /* noop for !CONFIG_BUFFER_HEAD */
return 0;
}
@@ -408,6 +399,16 @@ static const struct iomap_ops blkdev_iomap_ops = {
.iomap_begin = blkdev_iomap_begin,
};
#ifdef CONFIG_BUFFER_HEAD
static int blkdev_get_block(struct inode *inode, sector_t iblock,
struct buffer_head *bh, int create)
{
bh->b_bdev = I_BDEV(inode);
bh->b_blocknr = iblock;
set_buffer_mapped(bh);
return 0;
}
static int blkdev_writepage(struct page *page, struct writeback_control *wbc)
{
return block_write_full_page(page, blkdev_get_block, wbc);
@@ -453,6 +454,55 @@ const struct address_space_operations def_blk_aops = {
.migrate_folio = buffer_migrate_folio_norefs,
.is_dirty_writeback = buffer_check_dirty_writeback,
};
#else /* CONFIG_BUFFER_HEAD */
static int blkdev_read_folio(struct file *file, struct folio *folio)
{
return iomap_read_folio(folio, &blkdev_iomap_ops);
}
static void blkdev_readahead(struct readahead_control *rac)
{
iomap_readahead(rac, &blkdev_iomap_ops);
}
static int blkdev_map_blocks(struct iomap_writepage_ctx *wpc,
struct inode *inode, loff_t offset)
{
loff_t isize = i_size_read(inode);
if (WARN_ON_ONCE(offset >= isize))
return -EIO;
if (offset >= wpc->iomap.offset &&
offset < wpc->iomap.offset + wpc->iomap.length)
return 0;
return blkdev_iomap_begin(inode, offset, isize - offset,
IOMAP_WRITE, &wpc->iomap, NULL);
}
static const struct iomap_writeback_ops blkdev_writeback_ops = {
.map_blocks = blkdev_map_blocks,
};
static int blkdev_writepages(struct address_space *mapping,
struct writeback_control *wbc)
{
struct iomap_writepage_ctx wpc = { };
return iomap_writepages(mapping, wbc, &wpc, &blkdev_writeback_ops);
}
const struct address_space_operations def_blk_aops = {
.dirty_folio = filemap_dirty_folio,
.release_folio = iomap_release_folio,
.invalidate_folio = iomap_invalidate_folio,
.read_folio = blkdev_read_folio,
.readahead = blkdev_readahead,
.writepages = blkdev_writepages,
.is_partially_uptodate = iomap_is_partially_uptodate,
.error_remove_page = generic_error_remove_page,
.migrate_folio = filemap_migrate_folio,
};
#endif /* CONFIG_BUFFER_HEAD */
/*
* for a block special file file_inode(file)->i_size is zero