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From ea2675a74ab31ec9938dd50b4954ea9d6ba5fb50 Mon Sep 17 00:00:00 2001
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From: Max Reitz <mreitz@redhat.com>
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Date: Tue, 18 Nov 2014 15:30:17 +0100
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Subject: [PATCH 4/7] raw-posix: Fix raw_co_get_block_status() after EOF
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Message-id: <1416324620-16229-5-git-send-email-mreitz@redhat.com>
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Patchwork-id: 62439
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O-Subject: [RHEL-7.1/7.0.z qemu-kvm PATCH v3 4/7] raw-posix: Fix raw_co_get_block_status() after EOF
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Bugzilla: 1166605
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RH-Acked-by: Paolo Bonzini <pbonzini@redhat.com>
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RH-Acked-by: Kevin Wolf <kwolf@redhat.com>
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RH-Acked-by: Markus Armbruster <armbru@redhat.com>
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As its comment states, raw_co_get_block_status() should unconditionally
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return 0 and set *pnum to 0 for after EOF.
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An assertion after lseek(..., SEEK_HOLE) tried to catch this case by
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asserting that errno != -ENXIO (which would indicate a position after
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the EOF); but it should be errno != ENXIO instead. Regardless of that,
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there should be no such assertion at all. If bdrv_getlength() returned
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an outdated value and the image has been resized outside of qemu,
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lseek() will return with errno == ENXIO. Just return that value as an
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error then.
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Setting *pnum to 0 and returning 0 should not be done here, as in that
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case we should update the device length as well. So, from qemu's
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perspective, the file has not been resized; it's just that there was an
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error querying sectors beyond a certain point (the actual file size).
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Additionally, nb_sectors should be clamped against the image end. This
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was probably not an issue if FIEMAP or SEEK_HOLE/SEEK_DATA worked, but
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the fallback did not take this case into account.
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Reported-by: Kevin Wolf <kwolf@redhat.com>
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Signed-off-by: Max Reitz <mreitz@redhat.com>
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Reviewed-by: Eric Blake <eblake@redhat.com>
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Reviewed-by: Kevin Wolf <kwolf@redhat.com>
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Message-id: 1414148280-17949-2-git-send-email-mreitz@redhat.com
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Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
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(cherry picked from commit e6d7ec32dd315422a023ed3425fe36df8c274eeb)
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Signed-off-by: Max Reitz <mreitz@redhat.com>
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Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>
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---
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block/raw-posix.c | 14 ++++++++++----
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1 file changed, 10 insertions(+), 4 deletions(-)
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diff --git a/block/raw-posix.c b/block/raw-posix.c
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index 47b4b71..d04e683 100644
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--- a/block/raw-posix.c
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+++ b/block/raw-posix.c
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@@ -1314,10 +1314,6 @@ static int64_t try_seek_hole(BlockDriverState *bs, off_t start, off_t *data,
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*hole = lseek(s->fd, start, SEEK_HOLE);
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if (*hole == -1) {
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- /* -ENXIO indicates that sector_num was past the end of the file.
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- * There is a virtual hole there. */
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- assert(errno != -ENXIO);
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-
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return -errno;
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}
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@@ -1357,6 +1353,7 @@ static int64_t coroutine_fn raw_co_get_block_status(BlockDriverState *bs,
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int nb_sectors, int *pnum)
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{
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off_t start, data = 0, hole = 0;
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+ int64_t total_size;
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int64_t ret;
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ret = fd_open(bs);
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@@ -1365,6 +1362,15 @@ static int64_t coroutine_fn raw_co_get_block_status(BlockDriverState *bs,
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}
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start = sector_num * BDRV_SECTOR_SIZE;
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+ total_size = bdrv_getlength(bs);
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+ if (total_size < 0) {
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+ return total_size;
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+ } else if (start >= total_size) {
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+ *pnum = 0;
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+ return 0;
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+ } else if (start + nb_sectors * BDRV_SECTOR_SIZE > total_size) {
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+ nb_sectors = DIV_ROUND_UP(total_size - start, BDRV_SECTOR_SIZE);
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+ }
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ret = try_seek_hole(bs, start, &data, &hole, pnum);
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if (ret < 0) {
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--
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1.8.3.1
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