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linux/fs/xfs/xfs_exchrange.h

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xfs: introduce new file range exchange ioctl Introduce a new ioctl to handle exchanging ranges of bytes between files. The goal here is to perform the exchange atomically with respect to applications -- either they see the file contents before the exchange or they see that A-B is now B-A, even if the kernel crashes. My original goal with all this code was to make it so that online repair can build a replacement directory or xattr structure in a temporary file and commit the repair by atomically exchanging all the data blocks between the two files. However, I needed a way to test this mechanism thoroughly, so I've been evolving an ioctl interface since then. Signed-off-by: Darrick J. Wong <djwong@kernel.org> Reviewed-by: Christoph Hellwig <hch@lst.de>
2024-04-15 14:54:14 -07:00
/* SPDX-License-Identifier: GPL-2.0-or-later */
/*
* Copyright (c) 2020-2024 Oracle. All Rights Reserved.
* Author: Darrick J. Wong <djwong@kernel.org>
*/
#ifndef __XFS_EXCHRANGE_H__
#define __XFS_EXCHRANGE_H__
/* Update the mtime/cmtime of file1 and file2 */
#define __XFS_EXCHANGE_RANGE_UPD_CMTIME1 (1ULL << 63)
#define __XFS_EXCHANGE_RANGE_UPD_CMTIME2 (1ULL << 62)
xfs: introduce new file range commit ioctls This patch introduces two more new ioctls to manage atomic updates to file contents -- XFS_IOC_START_COMMIT and XFS_IOC_COMMIT_RANGE. The commit mechanism here is exactly the same as what XFS_IOC_EXCHANGE_RANGE does, but with the additional requirement that file2 cannot have changed since some sampling point. The start-commit ioctl performs the sampling of file attributes. Note: This patch currently samples i_ctime during START_COMMIT and checks that it hasn't changed during COMMIT_RANGE. This isn't entirely safe in kernels prior to 6.12 because ctime only had coarse grained granularity and very fast updates could collide with a COMMIT_RANGE. With the multi-granularity ctime introduced by Jeff Layton, it's now possible to update ctime such that this does not happen. It is critical, then, that this patch must not be backported to any kernel that does not support fine-grained file change timestamps. Signed-off-by: Darrick J. Wong <djwong@kernel.org> Acked-by: Jeff Layton <jlayton@kernel.org> Reviewed-by: Christoph Hellwig <hch@lst.de>
2024-08-30 15:36:47 -07:00
/* Freshness check required */
#define __XFS_EXCHANGE_RANGE_CHECK_FRESH2 (1ULL << 61)
xfs: introduce new file range exchange ioctl Introduce a new ioctl to handle exchanging ranges of bytes between files. The goal here is to perform the exchange atomically with respect to applications -- either they see the file contents before the exchange or they see that A-B is now B-A, even if the kernel crashes. My original goal with all this code was to make it so that online repair can build a replacement directory or xattr structure in a temporary file and commit the repair by atomically exchanging all the data blocks between the two files. However, I needed a way to test this mechanism thoroughly, so I've been evolving an ioctl interface since then. Signed-off-by: Darrick J. Wong <djwong@kernel.org> Reviewed-by: Christoph Hellwig <hch@lst.de>
2024-04-15 14:54:14 -07:00
#define XFS_EXCHANGE_RANGE_PRIV_FLAGS (__XFS_EXCHANGE_RANGE_UPD_CMTIME1 | \
xfs: introduce new file range commit ioctls This patch introduces two more new ioctls to manage atomic updates to file contents -- XFS_IOC_START_COMMIT and XFS_IOC_COMMIT_RANGE. The commit mechanism here is exactly the same as what XFS_IOC_EXCHANGE_RANGE does, but with the additional requirement that file2 cannot have changed since some sampling point. The start-commit ioctl performs the sampling of file attributes. Note: This patch currently samples i_ctime during START_COMMIT and checks that it hasn't changed during COMMIT_RANGE. This isn't entirely safe in kernels prior to 6.12 because ctime only had coarse grained granularity and very fast updates could collide with a COMMIT_RANGE. With the multi-granularity ctime introduced by Jeff Layton, it's now possible to update ctime such that this does not happen. It is critical, then, that this patch must not be backported to any kernel that does not support fine-grained file change timestamps. Signed-off-by: Darrick J. Wong <djwong@kernel.org> Acked-by: Jeff Layton <jlayton@kernel.org> Reviewed-by: Christoph Hellwig <hch@lst.de>
2024-08-30 15:36:47 -07:00
__XFS_EXCHANGE_RANGE_UPD_CMTIME2 | \
__XFS_EXCHANGE_RANGE_CHECK_FRESH2)
xfs: introduce new file range exchange ioctl Introduce a new ioctl to handle exchanging ranges of bytes between files. The goal here is to perform the exchange atomically with respect to applications -- either they see the file contents before the exchange or they see that A-B is now B-A, even if the kernel crashes. My original goal with all this code was to make it so that online repair can build a replacement directory or xattr structure in a temporary file and commit the repair by atomically exchanging all the data blocks between the two files. However, I needed a way to test this mechanism thoroughly, so I've been evolving an ioctl interface since then. Signed-off-by: Darrick J. Wong <djwong@kernel.org> Reviewed-by: Christoph Hellwig <hch@lst.de>
2024-04-15 14:54:14 -07:00
struct xfs_exchrange {
struct file *file1;
struct file *file2;
loff_t file1_offset;
loff_t file2_offset;
u64 length;
u64 flags; /* XFS_EXCHANGE_RANGE flags */
xfs: introduce new file range commit ioctls This patch introduces two more new ioctls to manage atomic updates to file contents -- XFS_IOC_START_COMMIT and XFS_IOC_COMMIT_RANGE. The commit mechanism here is exactly the same as what XFS_IOC_EXCHANGE_RANGE does, but with the additional requirement that file2 cannot have changed since some sampling point. The start-commit ioctl performs the sampling of file attributes. Note: This patch currently samples i_ctime during START_COMMIT and checks that it hasn't changed during COMMIT_RANGE. This isn't entirely safe in kernels prior to 6.12 because ctime only had coarse grained granularity and very fast updates could collide with a COMMIT_RANGE. With the multi-granularity ctime introduced by Jeff Layton, it's now possible to update ctime such that this does not happen. It is critical, then, that this patch must not be backported to any kernel that does not support fine-grained file change timestamps. Signed-off-by: Darrick J. Wong <djwong@kernel.org> Acked-by: Jeff Layton <jlayton@kernel.org> Reviewed-by: Christoph Hellwig <hch@lst.de>
2024-08-30 15:36:47 -07:00
/* file2 metadata for freshness checks */
u64 file2_ino;
struct timespec64 file2_mtime;
struct timespec64 file2_ctime;
u32 file2_gen;
xfs: introduce new file range exchange ioctl Introduce a new ioctl to handle exchanging ranges of bytes between files. The goal here is to perform the exchange atomically with respect to applications -- either they see the file contents before the exchange or they see that A-B is now B-A, even if the kernel crashes. My original goal with all this code was to make it so that online repair can build a replacement directory or xattr structure in a temporary file and commit the repair by atomically exchanging all the data blocks between the two files. However, I needed a way to test this mechanism thoroughly, so I've been evolving an ioctl interface since then. Signed-off-by: Darrick J. Wong <djwong@kernel.org> Reviewed-by: Christoph Hellwig <hch@lst.de>
2024-04-15 14:54:14 -07:00
};
long xfs_ioc_exchange_range(struct file *file,
struct xfs_exchange_range __user *argp);
xfs: introduce new file range commit ioctls This patch introduces two more new ioctls to manage atomic updates to file contents -- XFS_IOC_START_COMMIT and XFS_IOC_COMMIT_RANGE. The commit mechanism here is exactly the same as what XFS_IOC_EXCHANGE_RANGE does, but with the additional requirement that file2 cannot have changed since some sampling point. The start-commit ioctl performs the sampling of file attributes. Note: This patch currently samples i_ctime during START_COMMIT and checks that it hasn't changed during COMMIT_RANGE. This isn't entirely safe in kernels prior to 6.12 because ctime only had coarse grained granularity and very fast updates could collide with a COMMIT_RANGE. With the multi-granularity ctime introduced by Jeff Layton, it's now possible to update ctime such that this does not happen. It is critical, then, that this patch must not be backported to any kernel that does not support fine-grained file change timestamps. Signed-off-by: Darrick J. Wong <djwong@kernel.org> Acked-by: Jeff Layton <jlayton@kernel.org> Reviewed-by: Christoph Hellwig <hch@lst.de>
2024-08-30 15:36:47 -07:00
long xfs_ioc_start_commit(struct file *file,
struct xfs_commit_range __user *argp);
long xfs_ioc_commit_range(struct file *file,
struct xfs_commit_range __user *argp);
xfs: introduce new file range exchange ioctl Introduce a new ioctl to handle exchanging ranges of bytes between files. The goal here is to perform the exchange atomically with respect to applications -- either they see the file contents before the exchange or they see that A-B is now B-A, even if the kernel crashes. My original goal with all this code was to make it so that online repair can build a replacement directory or xattr structure in a temporary file and commit the repair by atomically exchanging all the data blocks between the two files. However, I needed a way to test this mechanism thoroughly, so I've been evolving an ioctl interface since then. Signed-off-by: Darrick J. Wong <djwong@kernel.org> Reviewed-by: Christoph Hellwig <hch@lst.de>
2024-04-15 14:54:14 -07:00
xfs: create deferred log items for file mapping exchanges Now that we've created the skeleton of a log intent item to track and restart file mapping exchange operations, add the upper level logic to commit intent items and turn them into concrete work recorded in the log. This builds on the existing bmap update intent items that have been around for a while now. Signed-off-by: Darrick J. Wong <djwong@kernel.org> Reviewed-by: Christoph Hellwig <hch@lst.de>
2024-04-15 14:54:17 -07:00
struct xfs_exchmaps_req;
void xfs_exchrange_ilock(struct xfs_trans *tp, struct xfs_inode *ip1,
struct xfs_inode *ip2);
void xfs_exchrange_iunlock(struct xfs_inode *ip1, struct xfs_inode *ip2);
int xfs_exchrange_estimate(struct xfs_exchmaps_req *req);
xfs: introduce new file range exchange ioctl Introduce a new ioctl to handle exchanging ranges of bytes between files. The goal here is to perform the exchange atomically with respect to applications -- either they see the file contents before the exchange or they see that A-B is now B-A, even if the kernel crashes. My original goal with all this code was to make it so that online repair can build a replacement directory or xattr structure in a temporary file and commit the repair by atomically exchanging all the data blocks between the two files. However, I needed a way to test this mechanism thoroughly, so I've been evolving an ioctl interface since then. Signed-off-by: Darrick J. Wong <djwong@kernel.org> Reviewed-by: Christoph Hellwig <hch@lst.de>
2024-04-15 14:54:14 -07:00
#endif /* __XFS_EXCHRANGE_H__ */
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