xfs: fix allocation length overflow in xfs_bmapi_write() (a99ebf43) · Commits · 戴 / test

When testing the new xfstests --large-fs option that does very large file preallocations, this assert was tripped deep in xfs_alloc_vextent(): XFS: Assertion failed: args->minlen <= args->maxlen, file: fs/xfs/xfs_alloc.c, line: 2239 The allocation was trying to allocate a zero length extent because the lower 32 bits of the allocation length was zero. The remaining length of the allocation to be done was an exact multiple of 2^32 - the first case I saw was at 496TB remaining to be allocated. This turns out to be an overflow when converting the allocation length (a 64 bit quantity) into the extent length to allocate (a 32 bit quantity), and it requires the length to be allocated an exact multiple of 2^32 blocks to trip the assert. Fix it by limiting the extent lenth to allocate to MAXEXTLEN. Signed-off-by:

Dave Chinner <dchinner@redhat.com> Signed-off-by:

Ben Myers <bpm@sgi.com> Reviewed-by:

Christoph Hellwig <hch@lst.de>

fs/xfs/xfs_bmap.c

+19 −1

Original line number	Diff line number	Diff line
		@@ -2383,6 +2383,8 @@ xfs_bmap_btalloc(
		int tryagain;
		int error;

		ASSERT(ap->length);

		mp = ap->ip->i_mount;
		align = ap->userdata ? xfs_get_extsz_hint(ap->ip) : 0;
		if (unlikely(align)) {
		@@ -4629,6 +4631,8 @@ xfs_bmapi_allocate(
		int error;
		int rt;

		ASSERT(bma->length > 0);

		rt = (whichfork == XFS_DATA_FORK) && XFS_IS_REALTIME_INODE(bma->ip);

		/*
		@@ -4849,6 +4853,7 @@ xfs_bmapi_write(
		ASSERT(*nmap <= XFS_BMAP_MAX_NMAP);
		ASSERT(!(flags & XFS_BMAPI_IGSTATE));
		ASSERT(tp != NULL);
		ASSERT(len > 0);

		whichfork = (flags & XFS_BMAPI_ATTRFORK) ?
		XFS_ATTR_FORK : XFS_DATA_FORK;
		@@ -4918,9 +4923,22 @@ xfs_bmapi_write(
		bma.eof = eof;
		bma.conv = !!(flags & XFS_BMAPI_CONVERT);
		bma.wasdel = wasdelay;
		bma.length = len;
		bma.offset = bno;

		/*
		* There's a 32/64 bit type mismatch between the
		* allocation length request (which can be 64 bits in
		* length) and the bma length request, which is
		* xfs_extlen_t and therefore 32 bits. Hence we have to
		* check for 32-bit overflows and handle them here.
		*/
		if (len > (xfs_filblks_t)MAXEXTLEN)
		bma.length = MAXEXTLEN;
		else
		bma.length = len;

		ASSERT(len > 0);
		ASSERT(bma.length > 0);
		error = xfs_bmapi_allocate(&bma, flags);
		if (error)
		goto error0;

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