From 69fe324e32aad7e1afc6ad14021a6a08ad52646c Mon Sep 17 00:00:00 2001 From: Max Reitz Date: Sat, 13 Jun 2015 16:22:27 +0200 Subject: [PATCH 33/42] block: Respect underlying file's EOF Message-id: <1434212556-3927-34-git-send-email-mreitz@redhat.com> Patchwork-id: 66052 O-Subject: [RHEL-7.2 qemu-kvm PATCH 33/42] block: Respect underlying file's EOF Bugzilla: 1129893 RH-Acked-by: Jeffrey Cody RH-Acked-by: Fam Zheng RH-Acked-by: Stefan Hajnoczi BZ: 1129893 When falling through to the underlying file in bdrv_co_get_block_status(), if it returns that the query offset is beyond the file end (by setting *pnum to 0), return the range to be zero and do not let the number of sectors for which information could be obtained be overwritten. Signed-off-by: Max Reitz Signed-off-by: Kevin Wolf (cherry picked from commit 59c9a95fd29cfb3296ee58e8a446df251d14a459) Signed-off-by: Max Reitz Signed-off-by: Miroslav Rezanina --- block.c | 15 +++++++++++++-- 1 file changed, 13 insertions(+), 2 deletions(-) diff --git a/block.c b/block.c index 22ab762..fa6e192 100644 --- a/block.c +++ b/block.c @@ -3797,13 +3797,24 @@ static int64_t coroutine_fn bdrv_co_get_block_status(BlockDriverState *bs, if (bs->file && (ret & BDRV_BLOCK_DATA) && !(ret & BDRV_BLOCK_ZERO) && (ret & BDRV_BLOCK_OFFSET_VALID)) { + int file_pnum; + ret2 = bdrv_co_get_block_status(bs->file, ret >> BDRV_SECTOR_BITS, - *pnum, pnum); + *pnum, &file_pnum); if (ret2 >= 0) { /* Ignore errors. This is just providing extra information, it * is useful but not necessary. */ - ret |= (ret2 & BDRV_BLOCK_ZERO); + if (!file_pnum) { + /* !file_pnum indicates an offset at or beyond the EOF; it is + * perfectly valid for the format block driver to point to such + * offsets, so catch it and mark everything as zero */ + ret |= BDRV_BLOCK_ZERO; + } else { + /* Limit request to the range reported by the protocol driver */ + *pnum = file_pnum; + ret |= (ret2 & BDRV_BLOCK_ZERO); + } } } -- 1.8.3.1