diff options
| -rw-r--r-- | include/linux/blkdev_compat.h | 16 |
1 files changed, 12 insertions, 4 deletions
diff --git a/include/linux/blkdev_compat.h b/include/linux/blkdev_compat.h index aa7e6b498..bff93ff54 100644 --- a/include/linux/blkdev_compat.h +++ b/include/linux/blkdev_compat.h @@ -326,6 +326,10 @@ bio_set_flags_failfast(struct block_device *bdev, int *flags) * and the new preflush behavior introduced in Linux 4.8. This is correct * in all cases but may have a performance impact for some kernels. It * has the advantage of minimizing kernel specific changes in the zvol code. + * + * Note that 2.6.32 era kernels provide both BIO_RW_BARRIER and REQ_FLUSH, + * where BIO_RW_BARRIER is the correct interface. Therefore, it is important + * that the HAVE_BIO_RW_BARRIER check occur before the REQ_FLUSH check. */ static inline boolean_t bio_is_flush(struct bio *bio) @@ -336,10 +340,10 @@ bio_is_flush(struct bio *bio) return (bio->bi_opf & REQ_PREFLUSH); #elif defined(REQ_PREFLUSH) && !defined(HAVE_BIO_BI_OPF) return (bio->bi_rw & REQ_PREFLUSH); -#elif defined(REQ_FLUSH) - return (bio->bi_rw & REQ_FLUSH); #elif defined(HAVE_BIO_RW_BARRIER) return (bio->bi_rw & (1 << BIO_RW_BARRIER)); +#elif defined(REQ_FLUSH) + return (bio->bi_rw & REQ_FLUSH); #else #error "Allowing the build will cause flush requests to be ignored. Please " "file an issue report at: https://github.com/zfsonlinux/zfs/issues/new" @@ -378,16 +382,20 @@ bio_is_fua(struct bio *bio) * * In all cases the normal I/O path is used for discards. The only * difference is how the kernel tags individual I/Os as discards. + * + * Note that 2.6.32 era kernels provide both BIO_RW_DISCARD and REQ_DISCARD, + * where BIO_RW_DISCARD is the correct interface. Therefore, it is important + * that the HAVE_BIO_RW_DISCARD check occur before the REQ_DISCARD check. */ static inline boolean_t bio_is_discard(struct bio *bio) { #if defined(HAVE_REQ_OP_DISCARD) return (bio_op(bio) == REQ_OP_DISCARD); -#elif defined(REQ_DISCARD) - return (bio->bi_rw & REQ_DISCARD); #elif defined(HAVE_BIO_RW_DISCARD) return (bio->bi_rw & (1 << BIO_RW_DISCARD)); +#elif defined(REQ_DISCARD) + return (bio->bi_rw & REQ_DISCARD); #else #error "Allowing the build will cause discard requests to become writes " "potentially triggering the DMU_MAX_ACCESS assertion. Please file " |