49391d1349
Online repair fixes metadata structures by writing a new copy out to disk and atomically committing the new structure into the filesystem. For this to work, we need to reserve all the space we're going to need ahead of time so that the atomic commit transaction is as small as possible. We also require the reserved space to be freed if the system goes down, or if we decide not to commit the repair, or if we reserve too much space. To keep the atomic commit transaction as small as possible, we would like to allocate some space and simultaneously schedule automatic reaping of the reserved space, even on log recovery. EFIs are the mechanism to get us there, but we need to use them in a novel manner. Once we allocate the space, we want to hold on to the EFI (relogging as necessary) until we can commit or cancel the repair. EFIs for written committed blocks need to go away, but unwritten or uncommitted blocks can be freed like normal. Earlier versions of this patchset directly manipulated the log items, but Dave thought that to be a layering violation. For v27, I've modified the defer ops handling code to be capable of pausing a deferred work item. Log intent items are created as they always have been, but paused items are pushed onto a side list when finishing deferred work items, and pushed back onto the transaction after that. Log intent done item are not created for paused work. The second part adds a "stale" flag to the EFI so that the repair reservation code can dispose of an EFI the normal way, but without the space actually being freed. This has been lightly tested with fstests. Enjoy! Signed-off-by: Darrick J. Wong <djwong@kernel.org> -----BEGIN PGP SIGNATURE----- iHUEABYKAB0WIQQ2qTKExjcn+O1o2YRKO3ySh0YRpgUCZXEx4wAKCRBKO3ySh0YR phIZAQCeUpGo77FqSuvgbXOcePgdsrKqSrhCYNxXQqbmTnX6BQEA09ir+SHoWKDy cvYZ2AEgllh8zJKJsXYi0YO6Y7qj6gQ= =FuaR -----END PGP SIGNATURE----- Merge tag 'repair-auto-reap-space-reservations-6.8_2023-12-06' of https://git.kernel.org/pub/scm/linux/kernel/git/djwong/xfs-linux into xfs-6.8-mergeA xfs: reserve disk space for online repairs Online repair fixes metadata structures by writing a new copy out to disk and atomically committing the new structure into the filesystem. For this to work, we need to reserve all the space we're going to need ahead of time so that the atomic commit transaction is as small as possible. We also require the reserved space to be freed if the system goes down, or if we decide not to commit the repair, or if we reserve too much space. To keep the atomic commit transaction as small as possible, we would like to allocate some space and simultaneously schedule automatic reaping of the reserved space, even on log recovery. EFIs are the mechanism to get us there, but we need to use them in a novel manner. Once we allocate the space, we want to hold on to the EFI (relogging as necessary) until we can commit or cancel the repair. EFIs for written committed blocks need to go away, but unwritten or uncommitted blocks can be freed like normal. Earlier versions of this patchset directly manipulated the log items, but Dave thought that to be a layering violation. For v27, I've modified the defer ops handling code to be capable of pausing a deferred work item. Log intent items are created as they always have been, but paused items are pushed onto a side list when finishing deferred work items, and pushed back onto the transaction after that. Log intent done item are not created for paused work. The second part adds a "stale" flag to the EFI so that the repair reservation code can dispose of an EFI the normal way, but without the space actually being freed. This has been lightly tested with fstests. Enjoy! Signed-off-by: Darrick J. Wong <djwong@kernel.org> Signed-off-by: Chandan Babu R <chandanbabu@kernel.org> * tag 'repair-auto-reap-space-reservations-6.8_2023-12-06' of https://git.kernel.org/pub/scm/linux/kernel/git/djwong/xfs-linux: xfs: force small EFIs for reaping btree extents xfs: log EFIs for all btree blocks being used to stage a btree xfs: implement block reservation accounting for btrees we're staging xfs: remove unused fields from struct xbtree_ifakeroot xfs: automatic freeing of freshly allocated unwritten space xfs: remove __xfs_free_extent_later xfs: allow pausing of pending deferred work items xfs: don't append work items to logged xfs_defer_pending objects
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.