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remove SWRITE* I/O types

Browse source 
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: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Christoph Hellwig 2010-08-11 17:06:24 +02:00 • committed by Al Viro
parent 87e99511ea
commit 9cb569d601
16 changed files with 73 additions and 94 deletions
Download patch file Download diff file Expand all files Collapse all files

52
fs/buffer.c
View file

@ -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
@ -2980,20 +2980,13 @@ 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);
submit_bh(WRITE, bh);
continue;
}
} else {
@ -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