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 If bdrv_getlength() returned an outdated value and the image has been resized outside of qemu, lseek() will return with errno == ENXIO.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