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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: Tristan Ye <tristan.ye@oracle.com>
Signed-off-by: Joel Becker <joel.becker@oracle.com>
This commit is contained in:
Tristan Ye 2010-12-07 14:35:07 +08:00 committed by Joel Becker
parent 388c4bcb4e
commit 39c99f12f1
3 changed files with 39 additions and 6 deletions
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7
fs/ocfs2/aops.c
View File

@ -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)

23
fs/ocfs2/aops.h
View File

@ -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 */

15
fs/ocfs2/file.c
View File

@ -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);