Commit 2496396f authored by Thomas Gleixner's avatar Thomas Gleixner Committed by Ingo Molnar
Browse files

sched/rt, fs: Use CONFIG_PREEMPTION 



CONFIG_PREEMPTION is selected by CONFIG_PREEMPT and by CONFIG_PREEMPT_RT.
Both PREEMPT and PREEMPT_RT require the same functionality which today
depends on CONFIG_PREEMPT.

Switch the i_size() and part_nr_sects_…() code over to use
CONFIG_PREEMPTION. Update the comment for fsstack_copy_inode_size() also
to refer to CONFIG_PREEMPTION.

[bigeasy: +PREEMPT comments]

Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Signed-off-by: default avatarSebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: linux-fsdevel@vger.kernel.org
Link: https://lore.kernel.org/r/20191015191821.11479-24-bigeasy@linutronix.de


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent d4a3dcbc

fs/stack.c

+3 −3
Original line number Diff line number Diff line
@@ -23,7 +23,7 @@ void fsstack_copy_inode_size(struct inode *dst, struct inode *src) 


	/*

	 * But on 32-bit, we ought to make an effort to keep the two halves of

	 * i_blocks in sync despite SMP or PREEMPT - though stat's

	 * i_blocks in sync despite SMP or PREEMPTION - though stat's

	 * generic_fillattr() doesn't bother, and we won't be applying quotas

	 * (where i_blocks does become important) at the upper level.

	 *
@@ -38,14 +38,14 @@ void fsstack_copy_inode_size(struct inode *dst, struct inode *src) 
		spin_unlock(&src->i_lock);



	/*

	 * If CONFIG_SMP or CONFIG_PREEMPT on 32-bit, it's vital for

	 * If CONFIG_SMP or CONFIG_PREEMPTION on 32-bit, it's vital for

	 * fsstack_copy_inode_size() to hold some lock around

	 * i_size_write(), otherwise i_size_read() may spin forever (see

	 * include/linux/fs.h).  We don't necessarily hold i_mutex when this

	 * is called, so take i_lock for that case.

	 *

	 * And if on 32-bit, continue our effort to keep the two halves of

	 * i_blocks in sync despite SMP or PREEMPT: use i_lock  for that case

	 * i_blocks in sync despite SMP or PREEMPTION: use i_lock for that case

	 * too, and do both at once by combining the tests.

	 *

	 * There is none of this locking overhead in the 64-bit case.

include/linux/fs.h

+2 −2
Original line number Diff line number Diff line
@@ -855,7 +855,7 @@ static inline loff_t i_size_read(const struct inode *inode) 
		i_size = inode->i_size;

	} while (read_seqcount_retry(&inode->i_size_seqcount, seq));

	return i_size;

#elif BITS_PER_LONG==32 && defined(CONFIG_PREEMPT)

#elif BITS_PER_LONG==32 && defined(CONFIG_PREEMPTION)

	loff_t i_size;



	preempt_disable();
@@ -880,7 +880,7 @@ static inline void i_size_write(struct inode *inode, loff_t i_size) 
	inode->i_size = i_size;

	write_seqcount_end(&inode->i_size_seqcount);

	preempt_enable();

#elif BITS_PER_LONG==32 && defined(CONFIG_PREEMPT)

#elif BITS_PER_LONG==32 && defined(CONFIG_PREEMPTION)

	preempt_disable();

	inode->i_size = i_size;

	preempt_enable();

include/linux/genhd.h

+3 −3
Original line number Diff line number Diff line
@@ -718,7 +718,7 @@ static inline void hd_free_part(struct hd_struct *part) 
 * accessor function.

 *

 * Code written along the lines of i_size_read() and i_size_write().

 * CONFIG_PREEMPT case optimizes the case of UP kernel with preemption

 * CONFIG_PREEMPTION case optimizes the case of UP kernel with preemption

 * on.

 */

static inline sector_t part_nr_sects_read(struct hd_struct *part)
@@ -731,7 +731,7 @@ static inline sector_t part_nr_sects_read(struct hd_struct *part) 
		nr_sects = part->nr_sects;

	} while (read_seqcount_retry(&part->nr_sects_seq, seq));

	return nr_sects;

#elif BITS_PER_LONG==32 && defined(CONFIG_PREEMPT)

#elif BITS_PER_LONG==32 && defined(CONFIG_PREEMPTION)

	sector_t nr_sects;



	preempt_disable();
@@ -754,7 +754,7 @@ static inline void part_nr_sects_write(struct hd_struct *part, sector_t size) 
	write_seqcount_begin(&part->nr_sects_seq);

	part->nr_sects = size;

	write_seqcount_end(&part->nr_sects_seq);

#elif BITS_PER_LONG==32 && defined(CONFIG_PREEMPT)

#elif BITS_PER_LONG==32 && defined(CONFIG_PREEMPTION)

	preempt_disable();

	part->nr_sects = size;

	preempt_enable();

CRA Git | Maintained and supported by SUSTech CRA and CCSE