[PATCH] xfs_io: fix extent array reallocation

[PATCH] xfs_io: fix extent array reallocation

[Christoph Hellwig]

From: Tomasz Majkowski <moosh009@gmail.com>

The XFS_IOC_FSGETXATTRA ioctl only returns the number of allocated
extents, so when we reallocate the extent array in the bmap command
we have to account for the worst case where there is a whole between
each two allocated extents.  Also add some slack to that case to
allow for a file growing while we are racing with it.


Index: xfsprogs-dev/io/bmap.c
===================================================================
--- xfsprogs-dev.orig/io/bmap.c	2009-03-20 06:28:33.000000000 +0000
+++ xfsprogs-dev/io/bmap.c	2009-03-20 06:29:52.000000000 +0000
@@ -217,8 +217,8 @@
 			exitcode = 1;
 			return 0;
 		}
-		if (fsx.fsx_nextents >= map_size-1) {
-			map_size = 2*(fsx.fsx_nextents+1);
+		if (2 * fsx.fsx_nextents > map_size) {
+			map_size = 2 * fsx.fsx_nextents + 1;
 			map = realloc(map, map_size*sizeof(*map));
 			if (map == NULL) {
 				fprintf(stderr,

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Re: [PATCH] xfs_io: fix extent array reallocation

[Felix Blyakher]

On Mar 20, 2009, at 2:26 AM, Christoph Hellwig wrote:

> From: Tomasz Majkowski <moosh009@gmail.com>
>
> The XFS_IOC_FSGETXATTRA ioctl only returns the number of allocated
> extents, so when we reallocate the extent array in the bmap command
> we have to account for the worst case where there is a whole between
> each two allocated extents.  Also add some slack to that case to
> allow for a file growing while we are racing with it.

Reviewed-by: Felix Blyakher <felixb@sgi.com>

>
>
>
> Index: xfsprogs-dev/io/bmap.c
> ===================================================================
> --- xfsprogs-dev.orig/io/bmap.c	2009-03-20 06:28:33.000000000 +0000
> +++ xfsprogs-dev/io/bmap.c	2009-03-20 06:29:52.000000000 +0000
> @@ -217,8 +217,8 @@
> 			exitcode = 1;
> 			return 0;
> 		}
> -		if (fsx.fsx_nextents >= map_size-1) {
> -			map_size = 2*(fsx.fsx_nextents+1);
> +		if (2 * fsx.fsx_nextents > map_size) {
> +			map_size = 2 * fsx.fsx_nextents + 1;
> 			map = realloc(map, map_size*sizeof(*map));
> 			if (map == NULL) {
> 				fprintf(stderr,
>
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