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authorLinus Torvalds <torvalds@linux-foundation.org>2024-09-16 09:14:02 +0200
committerLinus Torvalds <torvalds@linux-foundation.org>2024-09-16 09:14:02 +0200
commit3352633ce6b221d64bf40644d412d9670e7d56e3 (patch)
treef74add2d0a46ac33034955c1fa8dcff1cedd7dc0 /security
parentMerge tag 'vfs-6.12.folio' of gitolite.kernel.org:pub/scm/linux/kernel/git/vf... (diff)
parentMerge patch series "file: remove f_version" (diff)
downloadlinux-3352633ce6b221d64bf40644d412d9670e7d56e3.tar.xz
linux-3352633ce6b221d64bf40644d412d9670e7d56e3.zip
Merge tag 'vfs-6.12.file' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs
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 ...
Diffstat (limited to 'security')
-rw-r--r--security/selinux/hooks.c2
-rw-r--r--security/smack/smack_lsm.c2
2 files changed, 2 insertions, 2 deletions
diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index 400eca4ad0fb..cc123c6390a7 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -3950,7 +3950,7 @@ static int selinux_file_send_sigiotask(struct task_struct *tsk,
struct file_security_struct *fsec;
/* struct fown_struct is never outside the context of a struct file */
- file = container_of(fown, struct file, f_owner);
+ file = fown->file;
fsec = selinux_file(file);
diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c
index 002a1b9ed83a..eac7109be1db 100644
--- a/security/smack/smack_lsm.c
+++ b/security/smack/smack_lsm.c
@@ -1950,7 +1950,7 @@ static int smack_file_send_sigiotask(struct task_struct *tsk,
/*
* struct fown_struct is never outside the context of a struct file
*/
- file = container_of(fown, struct file, f_owner);
+ file = fown->file;
/* we don't log here as rc can be overriden */
blob = smack_file(file);