246 lines
9.7 KiB
Diff
246 lines
9.7 KiB
Diff
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From 2cb90b7798fa469f2d7d938ae88733eb1962d63d Mon Sep 17 00:00:00 2001
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From: Xavi Hernandez <xhernandez@gmail.com>
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Date: Fri, 9 Apr 2021 18:13:30 +0200
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Subject: [PATCH 554/584] dht: fix rebalance of sparse files
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Current implementation of rebalance for sparse files has a bug that,
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in some cases, causes a read of 0 bytes from the source subvolume.
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Posix xlator doesn't allow 0 byte reads and fails them with EINVAL,
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which causes rebalance to abort the migration.
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This patch implements a more robust way of finding data segments in
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a sparse file that avoids 0 byte reads, allowing the file to be
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migrated successfully.
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Backport of:
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> Upstream-patch: https://github.com/gluster/glusterfs/pull/2318
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> Fixes: #2317
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> Change-Id: Iff168dda2fb0f2edf716b21eb04cc2cc8ac3915c
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> Signed-off-by: Xavi Hernandez <xhernandez@redhat.com>
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BUG: 1957641
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Change-Id: Iff168dda2fb0f2edf716b21eb04cc2cc8ac3915c
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Signed-off-by: Xavi Hernandez <xhernandez@redhat.com>
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Reviewed-on: https://code.engineering.redhat.com/gerrit/c/rhs-glusterfs/+/244551
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Tested-by: RHGS Build Bot <nigelb@redhat.com>
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Reviewed-by: Sunil Kumar Heggodu Gopala Acharya <sheggodu@redhat.com>
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---
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tests/bugs/distribute/issue-2317.t | 29 ++++++++
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tests/volume.rc | 4 ++
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xlators/cluster/dht/src/dht-rebalance.c | 116 +++++++++++++++++---------------
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3 files changed, 93 insertions(+), 56 deletions(-)
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create mode 100755 tests/bugs/distribute/issue-2317.t
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diff --git a/tests/bugs/distribute/issue-2317.t b/tests/bugs/distribute/issue-2317.t
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new file mode 100755
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index 0000000..e29d003
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--- /dev/null
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+++ b/tests/bugs/distribute/issue-2317.t
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@@ -0,0 +1,29 @@
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+#!/bin/bash
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+
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+. $(dirname $0)/../../include.rc
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+. $(dirname $0)/../../volume.rc
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+
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+TESTS_EXPECTED_IN_LOOP=126
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+
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+cleanup
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+
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+TEST glusterd
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+TEST ${CLI} volume create ${V0} replica 3 ${H0}:/$B0/${V0}_{0..2}
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+TEST ${CLI} volume start ${V0}
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+
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+TEST ${GFS} --volfile-server ${H0} --volfile-id ${V0} ${M0}
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+
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+# Create several files to make sure that at least some of them should be
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+# migrated by rebalance.
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+for i in {0..63}; do
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+ TEST dd if=/dev/urandom of=${M0}/file.${i} bs=4k count=1
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+ TEST dd if=/dev/urandom of=${M0}/file.${i} bs=4k count=1 seek=128
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+done
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+
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+TEST ${CLI} volume add-brick ${V0} ${H0}:${B0}/${V0}_{3..5}
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+TEST ${CLI} volume rebalance ${V0} start force
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+EXPECT_WITHIN ${REBALANCE_TIMEOUT} "completed" rebalance_status_field "${V0}"
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+
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+EXPECT "^0$" rebalance_failed_field "${V0}"
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+
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+cleanup
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diff --git a/tests/volume.rc b/tests/volume.rc
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index 9a002d9..f5dd0b1 100644
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--- a/tests/volume.rc
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+++ b/tests/volume.rc
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@@ -75,6 +75,10 @@ function rebalance_status_field {
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$CLI volume rebalance $1 status | awk '{print $7}' | sed -n 3p
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}
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+function rebalance_failed_field {
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+ $CLI volume rebalance $1 status | awk '{print $5}' | sed -n 3p
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+}
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+
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function fix-layout_status_field {
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#The fix-layout status can be up to 3 words, (ex:'fix-layout in progress'), hence the awk-print $2 thru $4.
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#But if the status is less than 3 words, it also prints the next field i.e the run_time_in_secs.(ex:'completed 3.00').
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diff --git a/xlators/cluster/dht/src/dht-rebalance.c b/xlators/cluster/dht/src/dht-rebalance.c
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index 072896d..eab7558 100644
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--- a/xlators/cluster/dht/src/dht-rebalance.c
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+++ b/xlators/cluster/dht/src/dht-rebalance.c
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@@ -1024,6 +1024,46 @@ out:
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return ret;
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}
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+static int32_t
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+dht_rebalance_sparse_segment(xlator_t *subvol, fd_t *fd, off_t *offset,
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+ size_t *size)
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+{
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+ off_t hole;
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+ int32_t ret;
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+
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+ do {
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+ ret = syncop_seek(subvol, fd, *offset, GF_SEEK_DATA, NULL, offset);
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+ if (ret >= 0) {
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+ /* Starting at the offset of the last data segment, find the
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+ * next hole. After a data segment there should always be a
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+ * hole, since EOF is considered a hole. */
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+ ret = syncop_seek(subvol, fd, *offset, GF_SEEK_HOLE, NULL, &hole);
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+ }
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+
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+ if (ret < 0) {
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+ if (ret == -ENXIO) {
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+ /* This can happen if there are no more data segments (i.e.
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+ * the offset is at EOF), or there was a data segment but the
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+ * file has been truncated to a smaller size between both
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+ * seek requests. In both cases we are done. The file doesn't
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+ * contain more data. */
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+ ret = 0;
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+ }
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+ return ret;
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+ }
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+
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+ /* It could happen that at the same offset we detected data in the
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+ * first seek, there could be a hole in the second seek if user is
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+ * modifying the file concurrently. In this case we need to find a
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+ * new data segment to migrate. */
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+ } while (hole <= *offset);
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+
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+ /* Calculate the total size of the current data block */
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+ *size = hole - *offset;
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+
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+ return 1;
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+}
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+
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static int
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__dht_rebalance_migrate_data(xlator_t *this, gf_defrag_info_t *defrag,
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xlator_t *from, xlator_t *to, fd_t *src, fd_t *dst,
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@@ -1032,8 +1072,6 @@ __dht_rebalance_migrate_data(xlator_t *this, gf_defrag_info_t *defrag,
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int ret = 0;
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int count = 0;
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off_t offset = 0;
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- off_t data_offset = 0;
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- off_t hole_offset = 0;
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struct iovec *vector = NULL;
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struct iobref *iobref = NULL;
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uint64_t total = 0;
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@@ -1048,71 +1086,36 @@ __dht_rebalance_migrate_data(xlator_t *this, gf_defrag_info_t *defrag,
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while (total < ia_size) {
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/* This is a regular file - read it sequentially */
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if (!hole_exists) {
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- read_size = (((ia_size - total) > DHT_REBALANCE_BLKSIZE)
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- ? DHT_REBALANCE_BLKSIZE
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- : (ia_size - total));
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+ data_block_size = ia_size - total;
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} else {
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/* This is a sparse file - read only the data segments in the file
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*/
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/* If the previous data block is fully copied, find the next data
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- * segment
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- * starting at the offset of the last read and written byte, */
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+ * segment starting at the offset of the last read and written
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+ * byte. */
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if (data_block_size <= 0) {
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- ret = syncop_seek(from, src, offset, GF_SEEK_DATA, NULL,
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- &data_offset);
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- if (ret) {
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- if (ret == -ENXIO)
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- ret = 0; /* No more data segments */
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- else
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- *fop_errno = -ret; /* Error occurred */
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-
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+ ret = dht_rebalance_sparse_segment(from, src, &offset,
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+ &data_block_size);
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+ if (ret <= 0) {
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+ *fop_errno = -ret;
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break;
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}
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-
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- /* If the position of the current data segment is greater than
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- * the position of the next hole, find the next hole in order to
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- * calculate the length of the new data segment */
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- if (data_offset > hole_offset) {
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- /* Starting at the offset of the last data segment, find the
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- * next hole */
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- ret = syncop_seek(from, src, data_offset, GF_SEEK_HOLE,
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- NULL, &hole_offset);
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- if (ret) {
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- /* If an error occurred here it's a real error because
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- * if the seek for a data segment was successful then
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- * necessarily another hole must exist (EOF is a hole)
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- */
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- *fop_errno = -ret;
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- break;
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- }
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-
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- /* Calculate the total size of the current data block */
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- data_block_size = hole_offset - data_offset;
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- }
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- } else {
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- /* There is still data in the current segment, move the
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- * data_offset to the position of the last written byte */
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- data_offset = offset;
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}
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-
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- /* Calculate how much data needs to be read and written. If the data
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- * segment's length is bigger than DHT_REBALANCE_BLKSIZE, read and
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- * write DHT_REBALANCE_BLKSIZE data length and the rest in the
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- * next iteration(s) */
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- read_size = ((data_block_size > DHT_REBALANCE_BLKSIZE)
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- ? DHT_REBALANCE_BLKSIZE
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- : data_block_size);
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-
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- /* Calculate the remaining size of the data block - maybe there's no
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- * need to seek for data in the next iteration */
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- data_block_size -= read_size;
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-
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- /* Set offset to the offset of the data segment so read and write
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- * will have the correct position */
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- offset = data_offset;
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}
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+ /* Calculate how much data needs to be read and written. If the data
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+ * segment's length is bigger than DHT_REBALANCE_BLKSIZE, read and
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+ * write DHT_REBALANCE_BLKSIZE data length and the rest in the
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+ * next iteration(s) */
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+ read_size = ((data_block_size > DHT_REBALANCE_BLKSIZE)
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+ ? DHT_REBALANCE_BLKSIZE
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+ : data_block_size);
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+
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+ /* Calculate the remaining size of the data block - maybe there's no
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+ * need to seek for data in the next iteration */
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+ data_block_size -= read_size;
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+
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ret = syncop_readv(from, src, read_size, offset, 0, &vector, &count,
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&iobref, NULL, NULL, NULL);
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@@ -1177,6 +1180,7 @@ __dht_rebalance_migrate_data(xlator_t *this, gf_defrag_info_t *defrag,
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iobref = NULL;
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vector = NULL;
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}
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+
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if (iobref)
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iobref_unref(iobref);
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GF_FREE(vector);
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--
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1.8.3.1
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