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commit c7c539e8fd86de691475eea00409c6c030f312cd
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Author: Darrick J. Wong <darrick.wong@oracle.com>
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Date: Tue Jul 22 12:40:56 2014 -0400
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e4defrag: backwards-allocated files should be defragmented too
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Currently, e4defrag avoids increasing file fragmentation by comparing
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the number of runs of physical extents of both the original and the
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donor files. Unfortunately, there is a bug in the routine that counts
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physical extents, since it doesn't look at the logical block offsets
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of the extents. Therefore, a file whose blocks were allocated in
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reverse order will be seen as only having one big physical extent, and
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therefore will not be defragmented.
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Fix the counting routine to consider logical extent offset so that we
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defragment backwards-allocated files. This could be problematic if we
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ever gain the ability to lay out logically sparse extents in a
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physically contiguous manner, but presumably one wouldn't call defrag
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on such a file.
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Reported-by: Xiaoguang Wang <wangxg.fnst@cn.fujitsu.com>
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Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
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Signed-off-by: Theodore Ts'o <tytso@mit.edu>
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Index: e2fsprogs-1.42.9/misc/e4defrag.c
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===================================================================
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--- e2fsprogs-1.42.9.orig/misc/e4defrag.c
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+++ e2fsprogs-1.42.9/misc/e4defrag.c
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@@ -941,7 +941,9 @@ static int get_physical_count(struct fie
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do {
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if ((ext_list_tmp->data.physical + ext_list_tmp->data.len)
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- != ext_list_tmp->next->data.physical) {
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+ != ext_list_tmp->next->data.physical ||
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+ (ext_list_tmp->data.logical + ext_list_tmp->data.len)
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+ != ext_list_tmp->next->data.logical) {
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/* This extent and next extent are not continuous. */
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ret++;
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}
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