Commit 69448867 authored Jul 05, 2018 by Amir Goldstein Committed by Al Viro Jul 08, 2018

fs: shave 8 bytes off of struct inode

Here is a link to Linus' reply to Jan's concern about making
i_blkbibts byte addressable:
https://marc.info/?l=linux-fsdevel&m=152882624707975&w=2

Here is a link to an lkp.org report about potential performance
improvement in some workload, which could(?) be related to packing
i_blkbits closer to i_bytes/i_lock:
https://marc.info/?l=linux-fsdevel&m=153077048108198&w=2



Changes since v1:
- Add links to relevant discussions

Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

parent b7d3f17f

include/linux/fs.h

+3 −2

Original line number	Diff line number	Diff line
		@@ -275,6 +275,7 @@ struct writeback_control;

		/*
		* Write life time hint values.
		* Stored in struct inode as u8.
		*/
		enum rw_hint {
		WRITE_LIFE_NOT_SET = 0,
		@@ -609,8 +610,8 @@ struct inode {
		struct timespec64 i_ctime;
		spinlock_t i_lock; /* i_blocks, i_bytes, maybe i_size */
		unsigned short i_bytes;
		unsigned int i_blkbits;
		enum rw_hint i_write_hint;
		u8 i_blkbits;
		u8 i_write_hint;
		blkcnt_t i_blocks;

		#ifdef __NEED_I_SIZE_ORDERED

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