diff options
| author | Mateusz Guzik <mjguzik@gmail.com> | 2024-08-10 08:47:53 +0200 |
|---|---|---|
| committer | Christian Brauner <brauner@kernel.org> | 2024-08-30 08:22:36 +0200 |
| commit | 8447d848e1dc6d42d1dcd00f133d7715fc732c47 (patch) | |
| tree | ce84df5664c493a20b444ab48b694d076a1d61fc /include/linux/fs.h | |
| parent | 193b72792fdba54aa2af6c3ad72ce16c3f06b4f7 (diff) | |
vfs: only read fops once in fops_get/put
In do_dentry_open() the usage is:
f->f_op = fops_get(inode->i_fop);
In generated asm the compiler emits 2 reads from inode->i_fop instead of
just one.
This popped up due to false-sharing where loads from that offset end up
bouncing a cacheline during parallel open. While this is going to be fixed,
the spurious load does not need to be there.
This makes do_dentry_open() go down from 1177 to 1154 bytes.
fops_put() is patched to maintain some consistency.
No functional changes.
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Mateusz Guzik <mjguzik@gmail.com>
Link: https://lore.kernel.org/r/20240810064753.1211441-1-mjguzik@gmail.com
Signed-off-by: Christian Brauner <brauner@kernel.org>
Diffstat (limited to 'include/linux/fs.h')
| -rw-r--r-- | include/linux/fs.h | 15 |
1 files changed, 11 insertions, 4 deletions
diff --git a/include/linux/fs.h b/include/linux/fs.h index c0286d479c9d..696c620f90e0 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -2553,10 +2553,17 @@ struct super_block *sget(struct file_system_type *type, struct super_block *sget_dev(struct fs_context *fc, dev_t dev); /* Alas, no aliases. Too much hassle with bringing module.h everywhere */ -#define fops_get(fops) \ - (((fops) && try_module_get((fops)->owner) ? (fops) : NULL)) -#define fops_put(fops) \ - do { if (fops) module_put((fops)->owner); } while(0) +#define fops_get(fops) ({ \ + const struct file_operations *_fops = (fops); \ + (((_fops) && try_module_get((_fops)->owner) ? (_fops) : NULL)); \ +}) + +#define fops_put(fops) ({ \ + const struct file_operations *_fops = (fops); \ + if (_fops) \ + module_put((_fops)->owner); \ +}) + /* * This one is to be used *ONLY* from ->open() instances. * fops must be non-NULL, pinned down *and* module dependencies |