From 120235d6f5c85af2a0be17ad2705159e9d0b3adf Mon Sep 17 00:00:00 2001 From: Poornima G Date: Tue, 21 Jan 2014 23:50:23 +0000 Subject: cluster/dht: Fix layout sorting The layout was not being sorted in the ascending order leading to the wrong detection of holes/overlaps. From looking at the previous git commits it appears that the initial version itself had the err comparison code. Deductions from the current dht_layout_sort(): 1. The zero'ed out layouts should be in the from of list, if needed 2. The layout should be sorted in the ascending order of layout error value. 3. The layout should be sorted in the ascending order of the layout 'start'. But In some cases, with the err comparison code its not sorted in the ascending order. Example: If the input is as below for dht_layout_sort(), the sorting doesn't happen in ascending order. Input: 0-1 err:0 2-3 err:0 6-7 err:0 0-0 err:20 4-5 err:0 With the current sort, Output: 4-5 err:0 0-0 err:0 0-1 err:0 2-3 err:0 6-7 err:0 Expected: 0-0 err:20 0-1 err:0 2-3 err:0 4-5 err:0 6-7 err:0 Looking at dht_layout_anomalies() it appears that, it doesn't require the layout to be sorted based on error value. The other solution was to replace line 468 with: if ((layout->list[i].err || layout->list[j].err) && (layout->list[i].start > layout->list[j].start)) Since dht_layout_anomalies() didn't expect the layout to be sorted based on the error, removed the err comparison. Change-Id: I1215f6cd53efc7dba01c0958ba6cc7609dab6ff5 BUG: 1056406 Signed-off-by: Poornima G Reviewed-on: http://review.gluster.org/6757 Reviewed-by: Anand Avati Tested-by: Anand Avati --- xlators/cluster/dht/src/dht-layout.c | 23 ++++++++++++++++------- 1 file changed, 16 insertions(+), 7 deletions(-) (limited to 'xlators/cluster') diff --git a/xlators/cluster/dht/src/dht-layout.c b/xlators/cluster/dht/src/dht-layout.c index 1e38d6be1..31d85a506 100644 --- a/xlators/cluster/dht/src/dht-layout.c +++ b/xlators/cluster/dht/src/dht-layout.c @@ -465,11 +465,8 @@ dht_layout_entry_cmp (dht_layout_t *layout, int i, int j) - (int64_t) layout->list[j].stop; goto out; } - if (layout->list[i].err || layout->list[j].err) - diff = layout->list[i].err - layout->list[j].err; - else - diff = (int64_t) layout->list[i].start - - (int64_t) layout->list[j].start; + diff = (int64_t) layout->list[i].start + - (int64_t) layout->list[j].start; out: return diff; @@ -536,8 +533,20 @@ dht_layout_anomalies (xlator_t *this, loc_t *loc, dht_layout_t *layout, char is_virgin = 1; uint32_t no_space = 0; - /* TODO: explain what is happening */ - + /* This funtion scans through the layout spread of a directory to + check if there are any anomalies. Prior to calling this function + the layout entries should be sorted in the ascending order. + + If the layout entry has err != 0 + then increment the corresponding anomaly. + else + if (start of the current layout entry > stop + 1 of previous + non erroneous layout entry) + then it indicates a hole in the layout + if (start of the current layout entry < stop + 1 of previous + non erroneous layout entry) + then it indicates an overlap in the layout + */ last_stop = layout->list[0].start - 1; prev_stop = last_stop; -- cgit