Make direct IO code grab mapping range lock just before DIO is submitted
for the range under IO and release the lock once the IO is complete.
Signed-off-by: Jan Kara <j...@suse.cz>
---
fs/direct-io.c | 67 +++++++++++++++++++++++++++++++++++++++++++++++--------
1 files changed, 57 insertions(+), 10 deletions(-)
diff --git a/fs/direct-io.c b/fs/direct-io.c
index 3a430f3..1127ca5 100644
--- a/fs/direct-io.c
+++ b/fs/direct-io.c
@@ -56,10 +56,13 @@
* blocksize.
*/
+struct dio_bio_data;
+
/* dio_state only used in the submission path */
struct dio_submit {
struct bio *bio; /* bio under assembly */
+ struct dio_bio_data *bio_data; /* structure to be attached to the bio*/
unsigned blkbits; /* doesn't change */
unsigned blkfactor; /* When we're using an alignment which
is finer than the filesystem's soft
@@ -143,7 +146,17 @@ struct dio {
struct page *pages[DIO_PAGES]; /* page buffer */
} ____cacheline_aligned_in_smp;
+/*
+ * Structure associated with each submitted bio to provide back pointer and
+ * lock for the range accessed by the bio.
+ */
+struct dio_bio_data {
+ struct dio *dio;
+ struct range_lock lock;
+};
+
static struct kmem_cache *dio_cache __read_mostly;
+static struct kmem_cache *dio_bio_data_cache __read_mostly;
/*
* How many pages are in the queue?
@@ -275,10 +288,13 @@ static int dio_bio_complete(struct dio *dio, struct bio
*bio);
*/
static void dio_bio_end_aio(struct bio *bio, int error)
{
- struct dio *dio = bio->bi_private;
+ struct dio_bio_data *bio_data = bio->bi_private;
+ struct dio *dio = bio_data->dio;
unsigned long remaining;
unsigned long flags;
+ range_unlock(&dio->inode->i_mapping->mapping_lock, &bio_data->lock);
+ kmem_cache_free(dio_bio_data_cache, bio_data);
/* cleanup the bio */
dio_bio_complete(dio, bio);
@@ -298,14 +314,17 @@ static void dio_bio_end_aio(struct bio *bio, int error)
* The BIO completion handler simply queues the BIO up for the process-context
* handler.
*
- * During I/O bi_private points at the dio. After I/O, bi_private is used to
- * implement a singly-linked list of completed BIOs, at dio->bio_list.
+ * During I/O bi_private points at the dio_data. After I/O, bi_private is used
+ * to implement a singly-linked list of completed BIOs, at dio->bio_list.
*/
static void dio_bio_end_io(struct bio *bio, int error)
{
- struct dio *dio = bio->bi_private;
+ struct dio_bio_data *bio_data = bio->bi_private;
+ struct dio *dio = bio_data->dio;
unsigned long flags;
+ range_unlock(&dio->inode->i_mapping->mapping_lock, &bio_data->lock);
+ kmem_cache_free(dio_bio_data_cache, bio_data);
spin_lock_irqsave(&dio->bio_lock, flags);
bio->bi_private = dio->bio_list;
dio->bio_list = bio;
@@ -325,7 +344,8 @@ static void dio_bio_end_io(struct bio *bio, int error)
*/
void dio_end_io(struct bio *bio, int error)
{
- struct dio *dio = bio->bi_private;
+ struct dio_bio_data *bio_data = bio->bi_private;
+ struct dio *dio = bio_data->dio;
if (dio->is_async)
dio_bio_end_aio(bio, error);
@@ -369,8 +389,7 @@ static inline void dio_bio_submit(struct dio *dio, struct
dio_submit *sdio)
{
struct bio *bio = sdio->bio;
unsigned long flags;
-
- bio->bi_private = dio;
+ loff_t start = sdio->logical_offset_in_bio;
spin_lock_irqsave(&dio->bio_lock, flags);
dio->refcount++;
@@ -380,10 +399,30 @@ static inline void dio_bio_submit(struct dio *dio, struct
dio_submit *sdio)
bio_set_pages_dirty(bio);
if (sdio->submit_io)
- sdio->submit_io(dio->rw, bio, dio->inode,
- sdio->logical_offset_in_bio);
- else
+ sdio->submit_io(dio->rw, bio, dio->inode, start);
+ else {
+ struct address_space *mapping = dio->inode->i_mapping;
+ loff_t end = sdio->logical_offset_in_bio + bio->bi_size - 1;
+
+ sdio->bio_data->dio = dio;
+ range_lock_init(&sdio->bio_data->lock,
+ start >> PAGE_CACHE_SHIFT, end >> PAGE_CACHE_SHIFT);
+ range_lock(&mapping->mapping_lock, &sdio->bio_data->lock);
+ /*
+ * Once we hold mapping range lock writeout and invalidation
+ * cannot race with page faults of buffered IO.
+ */
+ filemap_write_and_wait_range(mapping, start, end);
+ if (dio->rw == WRITE && mapping->nrpages) {
+ invalidate_inode_pages2_range(mapping,
+ start >> PAGE_CACHE_SHIFT,
+ end >> PAGE_CACHE_SHIFT);
+ }
+ bio->bi_private = sdio->bio_data;
+ sdio->bio_data = NULL;
+
submit_bio(dio->rw, bio);
+ }
sdio->bio = NULL;
sdio->boundary = 0;
@@ -397,6 +436,8 @@ static inline void dio_cleanup(struct dio *dio, struct
dio_submit *sdio)
{
while (dio_pages_present(sdio))
page_cache_release(dio_get_page(dio, sdio));
+ if (sdio->bio_data)
+ kmem_cache_free(dio_bio_data_cache, sdio->bio_data);
}
/*
@@ -600,6 +641,11 @@ static inline int dio_new_bio(struct dio *dio, struct
dio_submit *sdio,
nr_pages = min(sdio->pages_in_io, bio_get_nr_vecs(map_bh->b_bdev));
nr_pages = min(nr_pages, BIO_MAX_PAGES);
BUG_ON(nr_pages <= 0);
+ sdio->bio_data = kmem_cache_alloc(dio_bio_data_cache, GFP_KERNEL);
+ if (!sdio->bio_data) {
+ ret = -ENOMEM;
+ goto out;
+ }
dio_bio_alloc(dio, sdio, map_bh->b_bdev, sector, nr_pages);
sdio->boundary = 0;
out:
@@ -1307,6 +1353,7 @@ EXPORT_SYMBOL(__blockdev_direct_IO);
static __init int dio_init(void)
{
dio_cache = KMEM_CACHE(dio, SLAB_PANIC);
+ dio_bio_data_cache = KMEM_CACHE(dio_bio_data, SLAB_PANIC);
return 0;
}
module_init(dio_init)
--
1.7.1
--
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