From: Daniel McNeil <[email protected]>
The direct I/O code is mapping the read request to the file system block. If
the file size was not on a block boundary, the result would show the the read
reading past EOF. This was only happening for the AIO case. The non-AIO case
truncates the result to match file size (in direct_io_worker). This patch
does the same thing for the AIO case, it truncates the result to match the
file size if the read reads past EOF.
When I/O completes the result can be truncated to match the file size
without using i_size_read(), thus the aio result now matches the number of
bytes read to the end of file.
Signed-off-by: Andrew Morton <[email protected]>
---
25-akpm/fs/direct-io.c | 20 +++++++++++++++++---
1 files changed, 17 insertions(+), 3 deletions(-)
diff -puN fs/direct-io.c~direct-io-async-short-read-fix fs/direct-io.c
--- 25/fs/direct-io.c~direct-io-async-short-read-fix 2005-04-12 03:21:36.288620192 -0700
+++ 25-akpm/fs/direct-io.c 2005-04-12 03:21:36.292619584 -0700
@@ -66,6 +66,7 @@ struct dio {
struct bio *bio; /* bio under assembly */
struct inode *inode;
int rw;
+ loff_t i_size; /* i_size when submitted */
int lock_type; /* doesn't change */
unsigned blkbits; /* doesn't change */
unsigned blkfactor; /* When we're using an alignment which
@@ -230,17 +231,29 @@ static void finished_one_bio(struct dio
spin_lock_irqsave(&dio->bio_lock, flags);
if (dio->bio_count == 1) {
if (dio->is_async) {
+ ssize_t transferred;
+ loff_t offset;
+
/*
* Last reference to the dio is going away.
* Drop spinlock and complete the DIO.
*/
spin_unlock_irqrestore(&dio->bio_lock, flags);
- dio_complete(dio, dio->block_in_file << dio->blkbits,
- dio->result);
+
+ /* Check for short read case */
+ transferred = dio->result;
+ offset = dio->iocb->ki_pos;
+
+ if ((dio->rw == READ) &&
+ ((offset + transferred) > dio->i_size))
+ transferred = dio->i_size - offset;
+
+ dio_complete(dio, offset, transferred);
+
/* Complete AIO later if falling back to buffered i/o */
if (dio->result == dio->size ||
((dio->rw == READ) && dio->result)) {
- aio_complete(dio->iocb, dio->result, 0);
+ aio_complete(dio->iocb, transferred, 0);
kfree(dio);
return;
} else {
@@ -951,6 +964,7 @@ direct_io_worker(int rw, struct kiocb *i
dio->page_errors = 0;
dio->result = 0;
dio->iocb = iocb;
+ dio->i_size = i_size_read(inode);
/*
* BIO completion state.
_
-
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