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linux/fs/xfs/xfs_buf_mem.h

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xfs: support in-memory buffer cache targets Allow the buffer cache to target in-memory files by making it possible to have a buftarg that maps pages from private shmem files. As the prevous patch alludes, the in-memory buftarg contains its own cache, points to a shmem file, and does not point to a block_device. The next few patches will make it possible to construct an xfs_btree in pageable memory by using this buftarg. Signed-off-by: Darrick J. Wong <djwong@kernel.org> Reviewed-by: Christoph Hellwig <hch@lst.de>
2024-02-22 23:43:21 +03:00
// SPDX-License-Identifier: GPL-2.0-or-later
/*
* Copyright (c) 2023-2024 Oracle. All Rights Reserved.
* Author: Darrick J. Wong <djwong@kernel.org>
*/
#ifndef __XFS_BUF_MEM_H__
#define __XFS_BUF_MEM_H__
#define XMBUF_BLOCKSIZE (PAGE_SIZE)
#define XMBUF_BLOCKSHIFT (PAGE_SHIFT)
#ifdef CONFIG_XFS_MEMORY_BUFS
static inline bool xfs_buftarg_is_mem(const struct xfs_buftarg *btp)
{
return btp->bt_bdev == NULL;
}
int xmbuf_alloc(struct xfs_mount *mp, const char *descr,
struct xfs_buftarg **btpp);
void xmbuf_free(struct xfs_buftarg *btp);
int xmbuf_map_page(struct xfs_buf *bp);
void xmbuf_unmap_page(struct xfs_buf *bp);
xfs: support in-memory btrees Adapt the generic btree cursor code to be able to create a btree whose buffers come from a (presumably in-memory) buftarg with a header block that's specific to in-memory btrees. We'll connect this to other parts of online scrub in the next patches. Note that in-memory btrees always have a block size matching the system memory page size for efficiency reasons. There are also a few things we need to do to finalize a btree update; that's covered in the next patch. Signed-off-by: Darrick J. Wong <djwong@kernel.org> Reviewed-by: Christoph Hellwig <hch@lst.de>
2024-02-22 23:43:35 +03:00
bool xmbuf_verify_daddr(struct xfs_buftarg *btp, xfs_daddr_t daddr);
xfs: launder in-memory btree buffers before transaction commit As we've noted in various places, all current users of in-memory btrees are online fsck. Online fsck only stages a btree long enough to rebuild an ondisk data structure, which means that the in-memory btree is ephemeral. Furthermore, if we encounter /any/ errors while updating an in-memory btree, all we do is tear down all the staged data and return an errno to userspace. In-memory btrees need not be transactional, so their buffers should not be committed to the ondisk log, nor should they be checkpointed by the AIL. That's just as well since the ephemeral nature of the btree means that the buftarg and the buffers may disappear quickly anyway. Therefore, we need a way to launder the btree buffers that get attached to the transaction by the generic btree code. Because the buffers are directly mapped to backing file pages, there's no need to bwrite them back to the tmpfs file. All we need to do is clean enough of the buffer log item state so that the bli can be detached from the buffer, remove the bli from the transaction's log item list, and reset the transaction dirty state as if the laundered items had never been there. For simplicity, create xfbtree transaction commit and cancel helpers that launder the in-memory btree buffers for callers. Once laundered, call the write verifier on non-stale buffers to avoid integrity issues, or punch a hole in the backing file for stale buffers. Signed-off-by: Darrick J. Wong <djwong@kernel.org> Reviewed-by: Christoph Hellwig <hch@lst.de>
2024-02-22 23:43:36 +03:00
void xmbuf_trans_bdetach(struct xfs_trans *tp, struct xfs_buf *bp);
int xmbuf_finalize(struct xfs_buf *bp);
xfs: support in-memory buffer cache targets Allow the buffer cache to target in-memory files by making it possible to have a buftarg that maps pages from private shmem files. As the prevous patch alludes, the in-memory buftarg contains its own cache, points to a shmem file, and does not point to a block_device. The next few patches will make it possible to construct an xfs_btree in pageable memory by using this buftarg. Signed-off-by: Darrick J. Wong <djwong@kernel.org> Reviewed-by: Christoph Hellwig <hch@lst.de>
2024-02-22 23:43:21 +03:00
#else
# define xfs_buftarg_is_mem(...) (false)
# define xmbuf_map_page(...) (-ENOMEM)
# define xmbuf_unmap_page(...) ((void)0)
xfs: support in-memory btrees Adapt the generic btree cursor code to be able to create a btree whose buffers come from a (presumably in-memory) buftarg with a header block that's specific to in-memory btrees. We'll connect this to other parts of online scrub in the next patches. Note that in-memory btrees always have a block size matching the system memory page size for efficiency reasons. There are also a few things we need to do to finalize a btree update; that's covered in the next patch. Signed-off-by: Darrick J. Wong <djwong@kernel.org> Reviewed-by: Christoph Hellwig <hch@lst.de>
2024-02-22 23:43:35 +03:00
# define xmbuf_verify_daddr(...) (false)
xfs: support in-memory buffer cache targets Allow the buffer cache to target in-memory files by making it possible to have a buftarg that maps pages from private shmem files. As the prevous patch alludes, the in-memory buftarg contains its own cache, points to a shmem file, and does not point to a block_device. The next few patches will make it possible to construct an xfs_btree in pageable memory by using this buftarg. Signed-off-by: Darrick J. Wong <djwong@kernel.org> Reviewed-by: Christoph Hellwig <hch@lst.de>
2024-02-22 23:43:21 +03:00
#endif /* CONFIG_XFS_MEMORY_BUFS */
#endif /* __XFS_BUF_MEM_H__ */
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