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Commit 9cb569d6 authored by Christoph Hellwig's avatar Christoph Hellwig Committed by Al Viro
Browse files

remove SWRITE* I/O types 



These flags aren't real I/O types, but tell ll_rw_block to always
lock the buffer instead of giving up on a failed trylock.

Instead add a new write_dirty_buffer helper that implements this semantic
and use it from the existing SWRITE* callers.  Note that the ll_rw_block
code had a bug where it didn't promote WRITE_SYNC_PLUG properly, which
this patch fixes.

In the ufs code clean up the helper that used to call ll_rw_block
to mirror sync_dirty_buffer, which is the function it implements for
compound buffers.

Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent 87e99511

fs/buffer.c

+29 −23
Original line number Diff line number Diff line
@@ -770,11 +770,12 @@ static int fsync_buffers_list(spinlock_t *lock, struct list_head *list) 
				spin_unlock(lock);

				/*

				 * Ensure any pending I/O completes so that

				 * ll_rw_block() actually writes the current

				 * contents - it is a noop if I/O is still in

				 * flight on potentially older contents.

				 * write_dirty_buffer() actually writes the

				 * current contents - it is a noop if I/O is

				 * still in flight on potentially older

				 * contents.

				 */

				ll_rw_block(SWRITE_SYNC_PLUG, 1, &bh);

				write_dirty_buffer(bh, WRITE_SYNC_PLUG);



				/*

				 * Kick off IO for the previous mapping. Note
@@ -2949,22 +2950,21 @@ EXPORT_SYMBOL(submit_bh); 


/**

 * ll_rw_block: low-level access to block devices (DEPRECATED)

 * @rw: whether to %READ or %WRITE or %SWRITE or maybe %READA (readahead)

 * @rw: whether to %READ or %WRITE or maybe %READA (readahead)

 * @nr: number of &struct buffer_heads in the array

 * @bhs: array of pointers to &struct buffer_head

 *

 * ll_rw_block() takes an array of pointers to &struct buffer_heads, and

 * requests an I/O operation on them, either a %READ or a %WRITE.  The third

 * %SWRITE is like %WRITE only we make sure that the *current* data in buffers

 * are sent to disk. The fourth %READA option is described in the documentation

 * for generic_make_request() which ll_rw_block() calls.

 * %READA option is described in the documentation for generic_make_request()

 * which ll_rw_block() calls.

 *

 * This function drops any buffer that it cannot get a lock on (with the

 * BH_Lock state bit) unless SWRITE is required, any buffer that appears to be

 * clean when doing a write request, and any buffer that appears to be

 * up-to-date when doing read request.  Further it marks as clean buffers that

 * are processed for writing (the buffer cache won't assume that they are

 * actually clean until the buffer gets unlocked).

 * BH_Lock state bit), any buffer that appears to be clean when doing a write

 * request, and any buffer that appears to be up-to-date when doing read

 * request.  Further it marks as clean buffers that are processed for

 * writing (the buffer cache won't assume that they are actually clean

 * until the buffer gets unlocked).

 *

 * ll_rw_block sets b_end_io to simple completion handler that marks

 * the buffer up-to-date (if approriate), unlocks the buffer and wakes
@@ -2980,19 +2980,12 @@ void ll_rw_block(int rw, int nr, struct buffer_head *bhs[]) 
	for (i = 0; i < nr; i++) {

		struct buffer_head *bh = bhs[i];



		if (rw == SWRITE || rw == SWRITE_SYNC || rw == SWRITE_SYNC_PLUG)

			lock_buffer(bh);

		else if (!trylock_buffer(bh))

		if (!trylock_buffer(bh))

			continue;



		if (rw == WRITE || rw == SWRITE || rw == SWRITE_SYNC ||

		    rw == SWRITE_SYNC_PLUG) {

		if (rw == WRITE) {

			if (test_clear_buffer_dirty(bh)) {

				bh->b_end_io = end_buffer_write_sync;

				get_bh(bh);

				if (rw == SWRITE_SYNC)

					submit_bh(WRITE_SYNC, bh);

				else

				submit_bh(WRITE, bh);

				continue;

			}
@@ -3009,6 +3002,19 @@ void ll_rw_block(int rw, int nr, struct buffer_head *bhs[]) 
}

EXPORT_SYMBOL(ll_rw_block);



void write_dirty_buffer(struct buffer_head *bh, int rw)

{

	lock_buffer(bh);

	if (!test_clear_buffer_dirty(bh)) {

		unlock_buffer(bh);

		return;

	}

	bh->b_end_io = end_buffer_write_sync;

	get_bh(bh);

	submit_bh(rw, bh);

}

EXPORT_SYMBOL(write_dirty_buffer);



/*

 * For a data-integrity writeout, we need to wait upon any in-progress I/O

 * and then start new I/O and then wait upon it.  The caller must have a ref on

fs/fat/misc.c

+3 −1
Original line number Diff line number Diff line
@@ -250,7 +250,9 @@ int fat_sync_bhs(struct buffer_head **bhs, int nr_bhs) 
{

	int i, err = 0;



	ll_rw_block(SWRITE, nr_bhs, bhs);

	for (i = 0; i < nr_bhs; i++)

		write_dirty_buffer(bhs[i], WRITE);



	for (i = 0; i < nr_bhs; i++) {

		wait_on_buffer(bhs[i]);

		if (buffer_eopnotsupp(bhs[i])) {

fs/jbd/checkpoint.c

+3 −1
Original line number Diff line number Diff line
@@ -254,7 +254,9 @@ __flush_batch(journal_t *journal, struct buffer_head **bhs, int *batch_count) 
{

	int i;



	ll_rw_block(SWRITE, *batch_count, bhs);

	for (i = 0; i < *batch_count; i++)

		write_dirty_buffer(bhs[i], WRITE);



	for (i = 0; i < *batch_count; i++) {

		struct buffer_head *bh = bhs[i];

		clear_buffer_jwrite(bh);

fs/jbd/journal.c

+1 −1
Original line number Diff line number Diff line
@@ -1024,7 +1024,7 @@ void journal_update_superblock(journal_t *journal, int wait) 
	if (wait)

		sync_dirty_buffer(bh);

	else

		ll_rw_block(SWRITE, 1, &bh);

		write_dirty_buffer(bh, WRITE);



out:

	/* If we have just flushed the log (by marking s_start==0), then

fs/jbd/revoke.c

+1 −1
Original line number Diff line number Diff line
@@ -617,7 +617,7 @@ static void flush_descriptor(journal_t *journal, 
	set_buffer_jwrite(bh);

	BUFFER_TRACE(bh, "write");

	set_buffer_dirty(bh);

	ll_rw_block((write_op == WRITE) ? SWRITE : SWRITE_SYNC_PLUG, 1, &bh);

	write_dirty_buffer(bh, write_op);

}

#endif