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libext2fs: fix block iterator for extents when truncating inodes 

When e2fsck uses the block iterator to release the blocks in an
extent-mapped inode, when the last block in an extent is removed, the
current extent has been removed and the extent cursor is now pointing
at the next inode.  But the block iterator code doesn't know that.  So
when it tries to go the next extent, it will end up skipping an
extent, and so the inode will be incompletely truncated.

The fix is to go to the next extent before calling the callback
function for the current extent.  This way, regardless of whether the
current extent gets removed, the extent cursor is still pointing at
the right place.

Reported-by: Andreas Dilger <adilger@whamcloud.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
bitmap-optimize
Theodore Ts'o 2012-06-12 00:27:39 -04:00
parent e9e96584b3
commit beb388a473
1 changed files with 17 additions and 2 deletions
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19
lib/ext2fs/block.c
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@ -389,7 +389,7 @@ errcode_t ext2fs_block_iterate3(ext2_filsys fs,
if (inode.i_flags & EXT4_EXTENTS_FL) {
ext2_extent_handle_t handle;
struct ext2fs_extent extent;
struct ext2fs_extent extent, next;
e2_blkcnt_t blockcnt = 0;
blk64_t blk, new_blk;
int op = EXT2_EXTENT_ROOT;
@ -401,7 +401,11 @@ errcode_t ext2fs_block_iterate3(ext2_filsys fs,
goto abort_exit;
while (1) {
ctx.errcode = ext2fs_extent_get(handle, op, &extent);
if (op == EXT2_EXTENT_CURRENT)
ctx.errcode = 0;
else
ctx.errcode = ext2fs_extent_get(handle, op,
&extent);
if (ctx.errcode) {
if (ctx.errcode != EXT2_ET_EXTENT_NO_NEXT)
break;
@ -456,6 +460,13 @@ errcode_t ext2fs_block_iterate3(ext2_filsys fs,
uninit = 0;
if (extent.e_flags & EXT2_EXTENT_FLAGS_UNINIT)
uninit = EXT2_EXTENT_SET_BMAP_UNINIT;
/*
* Get the next extent before we start messing
* with the current extent
*/
retval = ext2fs_extent_get(handle, op, &next);
#if 0
printf("lblk %llu pblk %llu len %d blockcnt %llu\n",
extent.e_lblk, extent.e_pblk,
@ -487,6 +498,10 @@ errcode_t ext2fs_block_iterate3(ext2_filsys fs,
if (ret & BLOCK_ABORT)
goto extent_done;
}
if (retval == 0) {
extent = next;
op = EXT2_EXTENT_CURRENT;
}
}
extent_done: