[f2fs-dev] [PATCH V4 4/8] fs/buffer.c: add decryption support via read_callbacks

[Chandan Rajendra]

This commit sets up read_callbacks context for buffer heads whose
contents need to be decrypted on endio.

Signed-off-by: Chandan Rajendra <chan...@linux.ibm.com>
---
 fs/buffer.c | 33 ++++++++++++++++++++++-----------
 1 file changed, 22 insertions(+), 11 deletions(-)

diff --git a/fs/buffer.c b/fs/buffer.c
index ce357602f471..96c4c9840746 100644
--- a/fs/buffer.c
+++ b/fs/buffer.c
@@ -45,6 +45,7 @@
 #include <linux/bit_spinlock.h>
 #include <linux/pagevec.h>
 #include <linux/sched/mm.h>
+#include <linux/read_callbacks.h>
 #include <trace/events/block.h>
 
 static int fsync_buffers_list(spinlock_t *lock, struct list_head *list);
@@ -245,11 +246,7 @@ __find_get_block_slow(struct block_device *bdev, sector_t 
block)
        return ret;
 }
 
-/*
- * I/O completion handler for block_read_full_page() - pages
- * which come unlocked at the end of I/O.
- */
-static void end_buffer_async_read(struct buffer_head *bh, int uptodate)
+void end_buffer_async_read(struct buffer_head *bh, int uptodate)
 {
        unsigned long flags;
        struct buffer_head *first;
@@ -257,8 +254,6 @@ static void end_buffer_async_read(struct buffer_head *bh, 
int uptodate)
        struct page *page;
        int page_uptodate = 1;
 
-       BUG_ON(!buffer_async_read(bh));
-
        page = bh->b_page;
        if (uptodate) {
                set_buffer_uptodate(bh);
@@ -306,6 +301,17 @@ static void end_buffer_async_read(struct buffer_head *bh, 
int uptodate)
        return;
 }
 
+/*
+ * I/O completion handler for block_read_full_page().  Pages are unlocked
+ * after the I/O completes and the read callbacks (if any) have executed.
+ */
+static void __end_buffer_async_read(struct buffer_head *bh, int uptodate)
+{
+       BUG_ON(!buffer_async_read(bh));
+
+       read_callbacks_endio_bh(bh, uptodate, end_buffer_async_read);
+}
+
 /*
  * Completion handler for block_write_full_page() - pages which are unlocked
  * during I/O, and which have PageWriteback cleared upon I/O completion.
@@ -378,7 +384,7 @@ EXPORT_SYMBOL(end_buffer_async_write);
  */
 static void mark_buffer_async_read(struct buffer_head *bh)
 {
-       bh->b_end_io = end_buffer_async_read;
+       bh->b_end_io = __end_buffer_async_read;
        set_buffer_async_read(bh);
 }
 
@@ -2293,10 +2299,15 @@ int block_read_full_page(struct page *page, get_block_t 
*get_block)
         */
        for (i = 0; i < nr; i++) {
                bh = arr[i];
-               if (buffer_uptodate(bh))
-                       end_buffer_async_read(bh, 1);
-               else
+               if (buffer_uptodate(bh)) {
+                       __end_buffer_async_read(bh, 1);
+               } else {
+                       if (WARN_ON(read_callbacks_setup_bh(inode, bh))) {
+                               __end_buffer_async_read(bh, 0);
+                               continue;
+                       }
                        submit_bh(REQ_OP_READ, 0, bh);
+               }
        }
        return 0;
 }
-- 
2.19.1



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