99 lines
3.4 KiB
Diff
99 lines
3.4 KiB
Diff
From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
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From: Tony Hutter <hutter2@llnl.gov>
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Date: Mon, 23 Oct 2023 14:45:06 -0700
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Subject: [PATCH] zvol: Remove broken blk-mq optimization
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This fix removes a dubious optimization in zfs_uiomove_bvec_rq()
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that saved the iterator contents of a rq_for_each_segment(). This
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optimization allowed restoring the "saved state" from a previous
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rq_for_each_segment() call on the same uio so that you wouldn't
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need to iterate though each bvec on every zfs_uiomove_bvec_rq() call.
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However, if the kernel is manipulating the requests/bios/bvecs under
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the covers between zfs_uiomove_bvec_rq() calls, then it could result
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in corruption from using the "saved state". This optimization
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results in an unbootable system after installing an OS on a zvol
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with blk-mq enabled.
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Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
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Signed-off-by: Tony Hutter <hutter2@llnl.gov>
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Closes #15351
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(cherry picked from commit 7c9b6fed16ed5034fd1cdfdaedfad93dc97b1557)
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Signed-off-by: Stoiko Ivanov <s.ivanov@proxmox.com>
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---
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include/os/linux/spl/sys/uio.h | 8 --------
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module/os/linux/zfs/zfs_uio.c | 29 -----------------------------
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2 files changed, 37 deletions(-)
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diff --git a/include/os/linux/spl/sys/uio.h b/include/os/linux/spl/sys/uio.h
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index cce097e16..a4b600004 100644
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--- a/include/os/linux/spl/sys/uio.h
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+++ b/include/os/linux/spl/sys/uio.h
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@@ -73,13 +73,6 @@ typedef struct zfs_uio {
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size_t uio_skip;
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struct request *rq;
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-
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- /*
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- * Used for saving rq_for_each_segment() state between calls
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- * to zfs_uiomove_bvec_rq().
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- */
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- struct req_iterator iter;
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- struct bio_vec bv;
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} zfs_uio_t;
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@@ -138,7 +131,6 @@ zfs_uio_bvec_init(zfs_uio_t *uio, struct bio *bio, struct request *rq)
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} else {
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uio->uio_bvec = NULL;
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uio->uio_iovcnt = 0;
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- memset(&uio->iter, 0, sizeof (uio->iter));
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}
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uio->uio_loffset = io_offset(bio, rq);
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diff --git a/module/os/linux/zfs/zfs_uio.c b/module/os/linux/zfs/zfs_uio.c
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index 3efd4ab15..c2ed67c43 100644
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--- a/module/os/linux/zfs/zfs_uio.c
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+++ b/module/os/linux/zfs/zfs_uio.c
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@@ -204,22 +204,6 @@ zfs_uiomove_bvec_rq(void *p, size_t n, zfs_uio_rw_t rw, zfs_uio_t *uio)
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this_seg_start = orig_loffset;
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rq_for_each_segment(bv, rq, iter) {
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- if (uio->iter.bio) {
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- /*
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- * If uio->iter.bio is present, then we know we've saved
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- * uio->iter from a previous call to this function, and
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- * we can skip ahead in this rq_for_each_segment() loop
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- * to where we last left off. That way, we don't need
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- * to iterate over tons of segments we've already
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- * processed - we can just restore the "saved state".
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- */
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- iter = uio->iter;
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- bv = uio->bv;
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- this_seg_start = uio->uio_loffset;
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- memset(&uio->iter, 0, sizeof (uio->iter));
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- continue;
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- }
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-
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/*
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* Lookup what the logical offset of the last byte of this
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* segment is.
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@@ -260,19 +244,6 @@ zfs_uiomove_bvec_rq(void *p, size_t n, zfs_uio_rw_t rw, zfs_uio_t *uio)
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copied = 1; /* We copied some data */
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}
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- if (n == 0) {
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- /*
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- * All done copying. Save our 'iter' value to the uio.
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- * This allows us to "save our state" and skip ahead in
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- * the rq_for_each_segment() loop the next time we call
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- * call zfs_uiomove_bvec_rq() on this uio (which we
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- * will be doing for any remaining data in the uio).
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- */
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- uio->iter = iter; /* make a copy of the struct data */
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- uio->bv = bv;
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- return (0);
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- }
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-
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this_seg_start = this_seg_end + 1;
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}
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