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Commit 39c99f12 authored by Tristan Ye's avatar Tristan Ye Committed by Joel Becker
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Ocfs2: Teach 'coherency=full' O_DIRECT writes to correctly up_read i_alloc_sem. 



Due to newly-introduced 'coherency=full' O_DIRECT writes also takes the EX
rw_lock like buffered writes did(rw_level == 1), it turns out messing the
usage of 'level' in ocfs2_dio_end_io() up, which caused i_alloc_sem being
failed to get up_read'd correctly.

This patch tries to teach ocfs2_dio_end_io to understand well on all locking
stuffs by explicitly introducing a new bit for i_alloc_sem in iocb's private
data, just like what we did for rw_lock.

Signed-off-by: default avatarTristan Ye <tristan.ye@oracle.com>
Signed-off-by: default avatarJoel Becker <joel.becker@oracle.com>
parent 388c4bcb

fs/ocfs2/aops.c

+5 −2
Original line number Diff line number Diff line
@@ -573,11 +573,14 @@ static void ocfs2_dio_end_io(struct kiocb *iocb, 
	/* this io's submitter should not have unlocked this before we could */

	BUG_ON(!ocfs2_iocb_is_rw_locked(iocb));



	if (ocfs2_iocb_is_sem_locked(iocb)) {

		up_read(&inode->i_alloc_sem);

		ocfs2_iocb_clear_sem_locked(iocb);

	}



	ocfs2_iocb_clear_rw_locked(iocb);



	level = ocfs2_iocb_rw_locked_level(iocb);

	if (!level)

		up_read(&inode->i_alloc_sem);

	ocfs2_rw_unlock(inode, level);



	if (is_async)

fs/ocfs2/aops.h

+21 −2
Original line number Diff line number Diff line
@@ -68,8 +68,27 @@ static inline void ocfs2_iocb_set_rw_locked(struct kiocb *iocb, int level) 
	else

		clear_bit(1, (unsigned long *)&iocb->private);

}



/*

 * Using a named enum representing lock types in terms of #N bit stored in

 * iocb->private, which is going to be used for communication bewteen

 * ocfs2_dio_end_io() and ocfs2_file_aio_write/read().

 */

enum ocfs2_iocb_lock_bits {

	OCFS2_IOCB_RW_LOCK = 0,

	OCFS2_IOCB_RW_LOCK_LEVEL,

	OCFS2_IOCB_SEM,

	OCFS2_IOCB_NUM_LOCKS

};



#define ocfs2_iocb_clear_rw_locked(iocb) \

	clear_bit(0, (unsigned long *)&iocb->private)

	clear_bit(OCFS2_IOCB_RW_LOCK, (unsigned long *)&iocb->private)

#define ocfs2_iocb_rw_locked_level(iocb) \

	test_bit(1, (unsigned long *)&iocb->private)

	test_bit(OCFS2_IOCB_RW_LOCK_LEVEL, (unsigned long *)&iocb->private)

#define ocfs2_iocb_set_sem_locked(iocb) \

	set_bit(OCFS2_IOCB_SEM, (unsigned long *)&iocb->private)

#define ocfs2_iocb_clear_sem_locked(iocb) \

	clear_bit(OCFS2_IOCB_SEM, (unsigned long *)&iocb->private)

#define ocfs2_iocb_is_sem_locked(iocb) \

	test_bit(OCFS2_IOCB_SEM, (unsigned long *)&iocb->private)

#endif /* OCFS2_FILE_H */

fs/ocfs2/file.c

+13 −2
Original line number Diff line number Diff line
@@ -2241,11 +2241,15 @@ static ssize_t ocfs2_file_aio_write(struct kiocb *iocb, 


	mutex_lock(&inode->i_mutex);



	ocfs2_iocb_clear_sem_locked(iocb);



relock:

	/* to match setattr's i_mutex -> i_alloc_sem -> rw_lock ordering */

	if (direct_io) {

		down_read(&inode->i_alloc_sem);

		have_alloc_sem = 1;

		/* communicate with ocfs2_dio_end_io */

		ocfs2_iocb_set_sem_locked(iocb);

	}



	/*
@@ -2382,8 +2386,10 @@ static ssize_t ocfs2_file_aio_write(struct kiocb *iocb, 
		ocfs2_rw_unlock(inode, rw_level);



out_sems:

	if (have_alloc_sem)

	if (have_alloc_sem) {

		up_read(&inode->i_alloc_sem);

		ocfs2_iocb_clear_sem_locked(iocb);

	}



	mutex_unlock(&inode->i_mutex);
@@ -2527,6 +2533,8 @@ static ssize_t ocfs2_file_aio_read(struct kiocb *iocb, 
		goto bail;

	}



	ocfs2_iocb_clear_sem_locked(iocb);



	/*

	 * buffered reads protect themselves in ->readpage().  O_DIRECT reads

	 * need locks to protect pending reads from racing with truncate.
@@ -2534,6 +2542,7 @@ static ssize_t ocfs2_file_aio_read(struct kiocb *iocb, 
	if (filp->f_flags & O_DIRECT) {

		down_read(&inode->i_alloc_sem);

		have_alloc_sem = 1;

		ocfs2_iocb_set_sem_locked(iocb);



		ret = ocfs2_rw_lock(inode, 0);

		if (ret < 0) {
@@ -2575,8 +2584,10 @@ static ssize_t ocfs2_file_aio_read(struct kiocb *iocb, 
	}



bail:

	if (have_alloc_sem)

	if (have_alloc_sem) {

		up_read(&inode->i_alloc_sem);

		ocfs2_iocb_clear_sem_locked(iocb);

	}

	if (rw_level != -1)

		ocfs2_rw_unlock(inode, rw_level);

	mlog_exit(ret);