kernel/linux.git/fs/affs, branch v6.12.80

affs: don't write overlarge OFS data block size fields

2025-04-10T12:39:29+00:00

[ Upstream commit 011ea742a25a77bac3d995f457886a67d178c6f0 ] If a data sector on an OFS floppy contains a value > 0x1e8 (the largest amount of data that fits in the sector after its header), then an Amiga reading the file can return corrupt data, by taking the overlarge size at its word and reading past the end of the buffer it read the disk sector into! The cause: when affs_write_end_ofs() writes data to an OFS filesystem, the new size field for a data block was computed by adding the amount of data currently being written (into the block) to the existing value of the size field. This is correct if you're extending the file at the end, but if you seek backwards in the file and overwrite _existing_ data, it can lead to the size field being larger than the maximum legal value. This commit changes the calculation so that it sets the size field to the max of its previous size and the position within the block that we just wrote up to. Signed-off-by: Simon Tatham Signed-off-by: David Sterba Signed-off-by: Sasha Levin

affs: generate OFS sequence numbers starting at 1

2025-04-10T12:39:29+00:00

[ Upstream commit e4cf8ec4de4e13f156c1d61977d282d90c221085 ] If I write a file to an OFS floppy image, and try to read it back on an emulated Amiga running Workbench 1.3, the Amiga reports a disk error trying to read the file. (That is, it's unable to read it _at all_, even to copy it to the NIL: device. It isn't a matter of getting the wrong data and being unable to parse the file format.) This is because the 'sequence number' field in the OFS data block header is supposed to be based at 1, but affs writes it based at 0. All three locations changed by this patch were setting the sequence number to a variable 'bidx' which was previously obtained by dividing a file position by bsize, so bidx will naturally use 0 for the first block. Therefore all three should add 1 to that value before writing it into the sequence number field. With this change, the Amiga successfully reads the file. For data block reference: https://wiki.osdev.org/FFS_(Amiga) Signed-off-by: Simon Tatham Signed-off-by: David Sterba Signed-off-by: Sasha Levin

Merge tag 'affs-for-6.12-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux

2024-09-16T11:07:59+00:00

Pull affs updates from David Sterba: "Cleanups removing unused code and updating the definition of a flexible struct array" * tag 'affs-for-6.12-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux: affs: Replace one-element array with flexible-array member affs: Remove unused macros GET_END_PTR, AFFS_GET_HASHENTRY

Merge tag 'vfs-6.12.file' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs

2024-09-16T07:14:02+00:00

Pull vfs file updates from Christian Brauner: "This is the work to cleanup and shrink struct file significantly. Right now, (focusing on x86) struct file is 232 bytes. After this series struct file will be 184 bytes aka 3 cacheline and a spare 8 bytes for future extensions at the end of the struct. With struct file being as ubiquitous as it is this should make a difference for file heavy workloads and allow further optimizations in the future. - struct fown_struct was embedded into struct file letting it take up 32 bytes in total when really it shouldn't even be embedded in struct file in the first place. Instead, actual users of struct fown_struct now allocate the struct on demand. This frees up 24 bytes. - Move struct file_ra_state into the union containg the cleanup hooks and move f_iocb_flags out of the union. This closes a 4 byte hole we created earlier and brings struct file to 192 bytes. Which means struct file is 3 cachelines and we managed to shrink it by 40 bytes. - Reorder struct file so that nothing crosses a cacheline. I suspect that in the future we will end up reordering some members to mitigate false sharing issues or just because someone does actually provide really good perf data. - Shrinking struct file to 192 bytes is only part of the work. Files use a slab that is SLAB_TYPESAFE_BY_RCU and when a kmem cache is created with SLAB_TYPESAFE_BY_RCU the free pointer must be located outside of the object because the cache doesn't know what part of the memory can safely be overwritten as it may be needed to prevent object recycling. That has the consequence that SLAB_TYPESAFE_BY_RCU may end up adding a new cacheline. So this also contains work to add a new kmem_cache_create_rcu() function that allows the caller to specify an offset where the freelist pointer is supposed to be placed. Thus avoiding the implicit addition of a fourth cacheline. - And finally this removes the f_version member in struct file. The f_version member isn't particularly well-defined. It is mainly used as a cookie to detect concurrent seeks when iterating directories. But it is also abused by some subsystems for completely unrelated things. It is mostly a directory and filesystem specific thing that doesn't really need to live in struct file and with its wonky semantics it really lacks a specific function. For pipes, f_version is (ab)used to defer poll notifications until a write has happened. And struct pipe_inode_info is used by multiple struct files in their ->private_data so there's no chance of pushing that down into file->private_data without introducing another pointer indirection. But pipes don't rely on f_pos_lock so this adds a union into struct file encompassing f_pos_lock and a pipe specific f_pipe member that pipes can use. This union of course can be extended to other file types and is similar to what we do in struct inode already" * tag 'vfs-6.12.file' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs: (26 commits) fs: remove f_version pipe: use f_pipe fs: add f_pipe ubifs: store cookie in private data ufs: store cookie in private data udf: store cookie in private data proc: store cookie in private data ocfs2: store cookie in private data input: remove f_version abuse ext4: store cookie in private data ext2: store cookie in private data affs: store cookie in private data fs: add generic_llseek_cookie() fs: use must_set_pos() fs: add must_set_pos() fs: add vfs_setpos_cookie() s390: remove unused f_version ceph: remove unused f_version adi: remove unused f_version mm: Removed @freeptr_offset to prevent doc warning ...

affs: store cookie in private data

2024-09-09T09:58:08+00:00

Store the cookie to detect concurrent seeks on directories in file->private_data. Link: https://lore.kernel.org/r/20240830-vfs-file-f_version-v1-9-6d3e4816aa7b@kernel.org Reviewed-by: Jan Kara Reviewed-by: Jeff Layton Signed-off-by: Christian Brauner

affs: Replace one-element array with flexible-array member

2024-09-06T15:48:15+00:00

Replace the deprecated one-element array with a modern flexible-array member in the struct affs_root_head. Add a comment that most struct members are not used, but kept as documentation. Link: https://github.com/KSPP/linux/issues/79 Signed-off-by: Thorsten Blum Reviewed-by: David Sterba Signed-off-by: David Sterba

affs: Remove unused macros GET_END_PTR, AFFS_GET_HASHENTRY

2024-09-06T15:48:14+00:00

The macros GET_END_PTR() and AFFS_GET_HASHENTRY() are not used anymore and can be removed. Remove them. Signed-off-by: Thorsten Blum Reviewed-by: David Sterba Signed-off-by: David Sterba

fs: Convert aops->write_begin to take a folio

2024-08-07T09:33:21+00:00

Convert all callers from working on a page to working on one page of a folio (support for working on an entire folio can come later). Removes a lot of folio->page->folio conversions. Reviewed-by: Josef Bacik Signed-off-by: Matthew Wilcox (Oracle) Signed-off-by: Christian Brauner

fs: Convert aops->write_end to take a folio

2024-08-07T09:32:02+00:00

Most callers have a folio, and most implementations operate on a folio, so remove the conversion from folio->page->folio to fit through this interface. Reviewed-by: Josef Bacik Signed-off-by: Matthew Wilcox (Oracle) Signed-off-by: Christian Brauner

affs: struct slink_front: Replace 1-element array with flexible array

2024-07-11T14:14:26+00:00

Replace the deprecated[1] use of a 1-element array in struct slink_front with a modern flexible array. No binary differences are present after this conversion. Link: https://github.com/KSPP/linux/issues/79 [1] Reviewed-by: Gustavo A. R. Silva Signed-off-by: Kees Cook Reviewed-by: David Sterba Signed-off-by: David Sterba