Add functions dm_bufio_issue_discard and dm_bufio_discard_buffers.
dm_bufio_issue_discard sends discard request to the underlying device.
dm_bufio_discard_buffers frees buffers in the range and then calls
dm_bufio_issue_discard.
Signed-off-by: Mikulas Patocka <mpatocka@xxxxxxxxxx>
---
drivers/md/dm-bufio.c | 50 +++++++++++++++++++++++++++++++++++++++++++++++
include/linux/dm-bufio.h | 12 +++++++++++
2 files changed, 62 insertions(+)
Index: linux-2.6/drivers/md/dm-bufio.c
===================================================================
--- linux-2.6.orig/drivers/md/dm-bufio.c 2020-02-07 17:14:08.000000000 +0100
+++ linux-2.6/drivers/md/dm-bufio.c 2020-02-07 17:29:42.000000000 +0100
@@ -1338,6 +1338,56 @@ int dm_bufio_issue_flush(struct dm_bufio
EXPORT_SYMBOL_GPL(dm_bufio_issue_flush);
/*
+ * Use dm-io to send a discard request to flush the device.
+ */
+int dm_bufio_issue_discard(struct dm_bufio_client *c, sector_t block, sector_t count)
+{
+ struct dm_io_request io_req = {
+ .bi_op = REQ_OP_DISCARD,
+ .bi_op_flags = REQ_SYNC,
+ .mem.type = DM_IO_KMEM,
+ .mem.ptr.addr = NULL,
+ .client = c->dm_io,
+ };
+ struct dm_io_region io_reg = {
+ .bdev = c->bdev,
+ .sector = block_to_sector(c, block),
+ .count = block_to_sector(c, count),
+ };
+
+ BUG_ON(dm_bufio_in_request());
+
+ return dm_io(&io_req, 1, &io_reg, NULL);
+}
+EXPORT_SYMBOL_GPL(dm_bufio_issue_discard);
+
+/*
+ * Free the specified range of buffers. If a buffer is held by other process, it
+ * is not freed. If a buffer is dirty, it is discarded without writeback.
+ * Finally, send the discard request to the device.
+ */
+int dm_bufio_discard_buffers(struct dm_bufio_client *c, sector_t block, sector_t count)
+{
+ sector_t i;
+
+ for (i = block; i < block + count; i++) {
+ struct dm_buffer *b;
+ dm_bufio_lock(c);
+ b = __find(c, i);
+ if (b && likely(!b->hold_count)) {
+ wait_on_bit_io(&b->state, B_READING, TASK_UNINTERRUPTIBLE);
+ wait_on_bit_io(&b->state, B_WRITING, TASK_UNINTERRUPTIBLE);
+ __unlink_buffer(b);
+ __free_buffer_wake(b);
+ }
+ dm_bufio_unlock(c);
+ }
+
+ return dm_bufio_issue_discard(c, block, count);
+}
+EXPORT_SYMBOL_GPL(dm_bufio_discard_buffers);
+
+/*
* We first delete any other buffer that may be at that new location.
*
* Then, we write the buffer to the original location if it was dirty.
Index: linux-2.6/include/linux/dm-bufio.h
===================================================================
--- linux-2.6.orig/include/linux/dm-bufio.h 2020-02-07 17:14:08.000000000 +0100
+++ linux-2.6/include/linux/dm-bufio.h 2020-02-07 17:29:46.000000000 +0100
@@ -126,6 +126,18 @@ int dm_bufio_write_dirty_buffers(struct
int dm_bufio_issue_flush(struct dm_bufio_client *c);
/*
+ * Send a discard request to the underlying device.
+ */
+int dm_bufio_issue_discard(struct dm_bufio_client *c, sector_t block, sector_t count);
+
+/*
+ * Free the specified range of buffers. If a buffer is held by other process, it
+ * is not freed. If a buffer is dirty, it is discarded without writeback.
+ * Finally, send the discard request to the device.
+ */
+int dm_bufio_discard_buffers(struct dm_bufio_client *c, sector_t block, sector_t count);
+
+/*
* Like dm_bufio_release but also move the buffer to the new
* block. dm_bufio_write_dirty_buffers is needed to commit the new block.
*/
--
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