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fs: switch f_iocb_flags and f_ra

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Now that we shrank struct file by 24 bytes we still have a 4 byte hole.
If we move struct file_ra_state into the union and f_iocb_flags out of
the union we close that whole and bring down struct file to 192 bytes.
Which means struct file is 3 cachelines and we managed to shrink it by
40 bytes this cycle.

I've tried to audit all codepaths that use f_ra and none of them seem to
rely on it in file->f_op->release() and never have since commit
1da177e4c3 ("Linux-2.6.12-rc2").

Link: https://lore.kernel.org/r/20240823-luftdicht-berappen-d69a2166a0db@brauner
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Christian Brauner <brauner@kernel.org>
This commit is contained in:
Christian Brauner 2024-08-22 16:14:46 +02:00
parent 1934b21261
commit a55d1cbd17
1 changed files with 3 additions and 3 deletions
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6
include/linux/fs.h
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@ -999,9 +999,9 @@ struct file {
struct callback_head f_task_work;
/* fput() must use workqueue (most kernel threads). */
struct llist_node f_llist;
unsigned int f_iocb_flags;
/* Invalid after last fput(). */
struct file_ra_state f_ra;
};
/*
* Protects f_ep, f_flags.
* Must not be taken from IRQ context.
@ -1012,9 +1012,9 @@ struct file {
struct mutex f_pos_lock;
loff_t f_pos;
unsigned int f_flags;
unsigned int f_iocb_flags;
struct fown_struct *f_owner;
const struct cred *f_cred;
struct file_ra_state f_ra;
struct path f_path;
struct inode *f_inode; /* cached value */
const struct file_operations *f_op;