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| author | Rob N <rob.norris@klarasystems.com> | 2024-04-12 16:00:20 +0000 |
|---|---|---|
| committer | GitHub <noreply@github.com> | 2024-04-12 16:00:20 +0000 |
| commit | b181b2e604de3f36feab1092c702cdec5e78c693 (patch) | |
| tree | fa7386b45105beececf3b210a910563d383a105e | |
| parent | d7605ae77b7ad176e8dbd5649fe4d14f5f4e8b9f (diff) | |
| download | src-b181b2e604de3f36feab1092c702cdec5e78c693.tar.gz src-b181b2e604de3f36feab1092c702cdec5e78c693.zip | |
bdev_discard_supported: understand discard_granularity=0
Kernel documentation for the discard_granularity property says:
A discard_granularity of 0 means that the device does not support
discard functionality.
Some older kernels had drivers (notably loop, but also some USB-SATA
adapters) that would set the QUEUE_FLAG_DISCARD capability flag, but
have discard_granularity=0. Since 5.10 (torvalds/linux@b35fd7422c2f) the
discard entry point blkdev_issue_discard() has had a check for this,
which would immediately reject the call with EOPNOTSUPP, and throw a
scary diagnostic message into the log. See #16068.
Since 6.8, the block layer sets a non-zero default for
discard_granularity (torvalds/linux@3c407dc723bb), and a future kernel
will remove the check entirely[1].
As such, there's no good reason for us to enable discard when
discard_granularity=0. The kernel will never let the request go in
anyway; better that we just disable it so we can report it properly to
the user.
1. https://patchwork.kernel.org/project/linux-block/patch/20240312144826.1045212-2-hch@lst.de/
Sponsored-by: Klara, Inc.
Sponsored-by: Wasabi Technology, Inc.
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Rob Norris <rob.norris@klarasystems.com>
Closes #16068
Closes #16082
| -rw-r--r-- | include/os/linux/kernel/linux/blkdev_compat.h | 6 |
1 files changed, 4 insertions, 2 deletions
diff --git a/include/os/linux/kernel/linux/blkdev_compat.h b/include/os/linux/kernel/linux/blkdev_compat.h index f111e648ccf7..b0f398354e4f 100644 --- a/include/os/linux/kernel/linux/blkdev_compat.h +++ b/include/os/linux/kernel/linux/blkdev_compat.h @@ -563,9 +563,11 @@ static inline boolean_t bdev_discard_supported(struct block_device *bdev) { #if defined(HAVE_BDEV_MAX_DISCARD_SECTORS) - return (!!bdev_max_discard_sectors(bdev)); + return (bdev_max_discard_sectors(bdev) > 0 && + bdev_discard_granularity(bdev) > 0); #elif defined(HAVE_BLK_QUEUE_DISCARD) - return (!!blk_queue_discard(bdev_get_queue(bdev))); + return (blk_queue_discard(bdev_get_queue(bdev)) > 0 && + bdev_get_queue(bdev)->limits.discard_granularity > 0); #else #error "Unsupported kernel" #endif |