bd_start_claiming duplicates a lot of the work done in __blkdev_get.
Integrate the two functions to avoid the duplicate work, and to do the
right thing for the md -ERESTARTSYS corner case.
Signed-off-by: Christoph Hellwig <hch@xxxxxx>
---
fs/block_dev.c | 177 +++++++++++++++----------------------------------
1 file changed, 55 insertions(+), 122 deletions(-)
diff --git a/fs/block_dev.c b/fs/block_dev.c
index 7075004d36997b..6fa987c77e0a1b 100644
--- a/fs/block_dev.c
+++ b/fs/block_dev.c
@@ -1078,72 +1078,6 @@ static struct gendisk *bdev_get_gendisk(struct block_device *bdev, int *partno)
return disk;
}
-/**
- * bd_start_claiming - start claiming a block device
- * @bdev: block device of interest
- * @holder: holder trying to claim @bdev
- *
- * @bdev is about to be opened exclusively. Check @bdev can be opened
- * exclusively and mark that an exclusive open is in progress. Each
- * successful call to this function must be matched with a call to
- * either bd_finish_claiming() or bd_abort_claiming() (which do not
- * fail).
- *
- * This function is used to gain exclusive access to the block device
- * without actually causing other exclusive open attempts to fail. It
- * should be used when the open sequence itself requires exclusive
- * access but may subsequently fail.
- *
- * CONTEXT:
- * Might sleep.
- *
- * RETURNS:
- * Pointer to the block device containing @bdev on success, ERR_PTR()
- * value on failure.
- */
-static struct block_device *bd_start_claiming(struct block_device *bdev,
- void *holder)
-{
- struct gendisk *disk;
- struct block_device *whole;
- int partno, err;
-
- might_sleep();
-
- /*
- * @bdev might not have been initialized properly yet, look up
- * and grab the outer block device the hard way.
- */
- disk = bdev_get_gendisk(bdev, &partno);
- if (!disk)
- return ERR_PTR(-ENXIO);
-
- /*
- * Normally, @bdev should equal what's returned from bdget_disk()
- * if partno is 0; however, some drivers (floppy) use multiple
- * bdev's for the same physical device and @bdev may be one of the
- * aliases. Keep @bdev if partno is 0. This means claimer
- * tracking is broken for those devices but it has always been that
- * way.
- */
- if (partno)
- whole = bdget_disk(disk, 0);
- else
- whole = bdgrab(bdev);
-
- put_disk_and_module(disk);
- if (!whole)
- return ERR_PTR(-ENOMEM);
-
- err = bd_prepare_to_claim(bdev, whole, holder);
- if (err) {
- bdput(whole);
- return ERR_PTR(err);
- }
-
- return whole;
-}
-
static void bd_clear_claiming(struct block_device *whole, void *holder)
{
lockdep_assert_held(&bdev_lock);
@@ -1156,7 +1090,7 @@ static void bd_clear_claiming(struct block_device *whole, void *holder)
/**
* bd_finish_claiming - finish claiming of a block device
* @bdev: block device of interest
- * @whole: whole block device (returned from bd_start_claiming())
+ * @whole: whole block device
* @holder: holder that has claimed @bdev
*
* Finish exclusive open of a block device. Mark the device as exlusively
@@ -1182,7 +1116,7 @@ static void bd_finish_claiming(struct block_device *bdev,
/**
* bd_abort_claiming - abort claiming of a block device
* @bdev: block device of interest
- * @whole: whole block device (returned from bd_start_claiming())
+ * @whole: whole block device
* @holder: holder that has claimed @bdev
*
* Abort claiming of a block device when the exclusive open failed. This can be
@@ -1521,13 +1455,15 @@ EXPORT_SYMBOL_GPL(bdev_disk_changed);
* mutex_lock_nested(whole->bd_mutex, 1)
*/
-static int __blkdev_get(struct block_device *bdev, fmode_t mode, int for_part)
+static int __blkdev_get(struct block_device *bdev, fmode_t mode, void *holder,
+ int for_part)
{
+ struct block_device *whole = NULL, *claiming = NULL;
struct gendisk *disk;
int ret;
int partno;
int perm = 0;
- bool first_open = false, need_restart;
+ bool first_open = false, unblock_events = true, need_restart;
if (mode & FMODE_READ)
perm |= MAY_READ;
@@ -1549,6 +1485,25 @@ static int __blkdev_get(struct block_device *bdev, fmode_t mode, int for_part)
if (!disk)
goto out;
+ if (partno) {
+ whole = bdget_disk(disk, 0);
+ if (!whole) {
+ ret = -ENOMEM;
+ goto out_put_disk;
+ }
+ }
+
+ if (!for_part && (mode & FMODE_EXCL)) {
+ WARN_ON_ONCE(!holder);
+ if (whole)
+ claiming = whole;
+ else
+ claiming = bdev;
+ ret = bd_prepare_to_claim(bdev, claiming, holder);
+ if (ret)
+ goto out_put_whole;
+ }
+
disk_block_events(disk);
mutex_lock_nested(&bdev->bd_mutex, for_part);
if (!bdev->bd_openers) {
@@ -1592,18 +1547,11 @@ static int __blkdev_get(struct block_device *bdev, fmode_t mode, int for_part)
if (ret)
goto out_clear;
} else {
- struct block_device *whole;
- whole = bdget_disk(disk, 0);
- ret = -ENOMEM;
- if (!whole)
- goto out_clear;
BUG_ON(for_part);
- ret = __blkdev_get(whole, mode, 1);
- if (ret) {
- bdput(whole);
+ ret = __blkdev_get(whole, mode, NULL, 1);
+ if (ret)
goto out_clear;
- }
- bdev->bd_contains = whole;
+ bdev->bd_contains = bdgrab(whole);
bdev->bd_part = disk_get_part(disk, partno);
if (!(disk->flags & GENHD_FL_UP) ||
!bdev->bd_part || !bdev->bd_part->nr_sects) {
@@ -1632,11 +1580,30 @@ static int __blkdev_get(struct block_device *bdev, fmode_t mode, int for_part)
bdev->bd_openers++;
if (for_part)
bdev->bd_part_count++;
+ if (claiming)
+ bd_finish_claiming(bdev, claiming, holder);
+
+ /*
+ * Block event polling for write claims if requested. Any write holder
+ * makes the write_holder state stick until all are released. This is
+ * good enough and tracking individual writeable reference is too
+ * fragile given the way @mode is used in blkdev_get/put().
+ */
+ if (claiming && (mode & FMODE_WRITE) && !bdev->bd_write_holder &&
+ (disk->flags & GENHD_FL_BLOCK_EVENTS_ON_EXCL_WRITE)) {
+ bdev->bd_write_holder = true;
+ unblock_events = false;
+ }
mutex_unlock(&bdev->bd_mutex);
- disk_unblock_events(disk);
+
+ if (unblock_events)
+ disk_unblock_events(disk);
+
/* only one opener holds refs to the module and disk */
if (!first_open)
put_disk_and_module(disk);
+ if (whole)
+ bdput(whole);
return 0;
out_clear:
@@ -1647,13 +1614,18 @@ static int __blkdev_get(struct block_device *bdev, fmode_t mode, int for_part)
__blkdev_put(bdev->bd_contains, mode, 1);
bdev->bd_contains = NULL;
out_unlock_bdev:
+ if (claiming)
+ bd_abort_claiming(bdev, claiming, holder);
mutex_unlock(&bdev->bd_mutex);
disk_unblock_events(disk);
+ out_put_whole:
+ if (whole)
+ bdput(whole);
+ out_put_disk:
put_disk_and_module(disk);
if (need_restart)
goto restart;
out:
-
return ret;
}
@@ -1678,50 +1650,11 @@ static int __blkdev_get(struct block_device *bdev, fmode_t mode, int for_part)
*/
int blkdev_get(struct block_device *bdev, fmode_t mode, void *holder)
{
- struct block_device *whole = NULL;
int res;
- WARN_ON_ONCE((mode & FMODE_EXCL) && !holder);
-
- if ((mode & FMODE_EXCL) && holder) {
- whole = bd_start_claiming(bdev, holder);
- if (IS_ERR(whole)) {
- bdput(bdev);
- return PTR_ERR(whole);
- }
- }
-
- res = __blkdev_get(bdev, mode, 0);
-
- if (whole) {
- struct gendisk *disk = whole->bd_disk;
-
- /* finish claiming */
- mutex_lock(&bdev->bd_mutex);
- if (!res)
- bd_finish_claiming(bdev, whole, holder);
- else
- bd_abort_claiming(bdev, whole, holder);
- /*
- * Block event polling for write claims if requested. Any
- * write holder makes the write_holder state stick until
- * all are released. This is good enough and tracking
- * individual writeable reference is too fragile given the
- * way @mode is used in blkdev_get/put().
- */
- if (!res && (mode & FMODE_WRITE) && !bdev->bd_write_holder &&
- (disk->flags & GENHD_FL_BLOCK_EVENTS_ON_EXCL_WRITE)) {
- bdev->bd_write_holder = true;
- disk_block_events(disk);
- }
-
- mutex_unlock(&bdev->bd_mutex);
- bdput(whole);
- }
-
+ res =__blkdev_get(bdev, mode, holder, 0);
if (res)
bdput(bdev);
-
return res;
}
EXPORT_SYMBOL(blkdev_get);
--
2.26.2
