tree 59f34811d18fef8195bc3200bdb2684598175f29
parent e6c9f5c1888097c936334bf9740024520ca47b8e
author Jan Kara <[EMAIL PROTECTED]> Wed, 07 Sep 2005 05:19:10 -0700
committer Linus Torvalds <[EMAIL PROTECTED]> Thu, 08 Sep 2005 06:57:55 -0700
[PATCH] Make ll_rw_block() wait for buffer lock
Introduce new ll_rw_block() operation SWRITE meaning that block layer should
wait for the buffer lock and write-out afterwards. Hence data in buffers at
the time of call are guaranteed to be submitted to the disk.
Signed-off-by: Jan Kara <[EMAIL PROTECTED]>
Signed-off-by: Andrew Morton <[EMAIL PROTECTED]>
Signed-off-by: Linus Torvalds <[EMAIL PROTECTED]>
fs/buffer.c | 30 ++++++++++++++++--------------
include/linux/fs.h | 1 +
2 files changed, 17 insertions(+), 14 deletions(-)
diff --git a/fs/buffer.c b/fs/buffer.c
--- a/fs/buffer.c
+++ b/fs/buffer.c
@@ -917,8 +917,7 @@ static int fsync_buffers_list(spinlock_t
* contents - it is a noop if I/O is still in
* flight on potentially older contents.
*/
- wait_on_buffer(bh);
- ll_rw_block(WRITE, 1, &bh);
+ ll_rw_block(SWRITE, 1, &bh);
brelse(bh);
spin_lock(lock);
}
@@ -2793,21 +2792,22 @@ int submit_bh(int rw, struct buffer_head
/**
* ll_rw_block: low-level access to block devices (DEPRECATED)
- * @rw: whether to %READ or %WRITE or maybe %READA (readahead)
+ * @rw: whether to %READ or %WRITE or %SWRITE 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 %READA option is described in the documentation for
- * generic_make_request() which ll_rw_block() calls.
+ * 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.
*
* This function drops any buffer that it cannot get a lock on (with the
- * 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).
+ * 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).
*
* 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
@@ -2823,11 +2823,13 @@ void ll_rw_block(int rw, int nr, struct
for (i = 0; i < nr; i++) {
struct buffer_head *bh = bhs[i];
- if (test_set_buffer_locked(bh))
+ if (rw == SWRITE)
+ lock_buffer(bh);
+ else if (test_set_buffer_locked(bh))
continue;
get_bh(bh);
- if (rw == WRITE) {
+ if (rw == WRITE || rw == SWRITE) {
if (test_clear_buffer_dirty(bh)) {
bh->b_end_io = end_buffer_write_sync;
submit_bh(WRITE, bh);
diff --git a/include/linux/fs.h b/include/linux/fs.h
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -69,6 +69,7 @@ extern int dir_notify_enable;
#define READ 0
#define WRITE 1
#define READA 2 /* read-ahead - don't block if no resources */
+#define SWRITE 3 /* for ll_rw_block() - wait for buffer lock */
#define SPECIAL 4 /* For non-blockdevice requests in request queue */
#define READ_SYNC (READ | (1 << BIO_RW_SYNC))
#define WRITE_SYNC (WRITE | (1 << BIO_RW_SYNC))
-
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