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Subject[PATCH 1/2] gfs2: remove usage of list iterator variable for list_for_each_entry_continue()
Date
In preparation to limiting the scope of a list iterator to the list
traversal loop, use a dedicated pointer to iterate through the list [1].

Since that variable should not be used past the loop iteration, a
separate variable is used to 'remember the current location within the
loop'.

To either continue iterating from that position or start a new
iteration (if the previous iteration was complete) list_prepare_entry()
is used.

Link: https://lore.kernel.org/all/CAHk-=wgRr_D8CB-D9Kg-c=EHreAsk5SqXPwr9Y7k9sA6cWXJ6w@mail.gmail.com/ [1]
Signed-off-by: Jakob Koschel <jakobkoschel@gmail.com>
---
fs/gfs2/lops.c | 16 ++++++++++++----
1 file changed, 12 insertions(+), 4 deletions(-)

diff --git a/fs/gfs2/lops.c b/fs/gfs2/lops.c
index 6ba51cbb94cf..74e6d05cee2c 100644
--- a/fs/gfs2/lops.c
+++ b/fs/gfs2/lops.c
@@ -653,7 +653,7 @@ static void gfs2_before_commit(struct gfs2_sbd *sdp, unsigned int limit,
bool is_databuf)
{
struct gfs2_log_descriptor *ld;
- struct gfs2_bufdata *bd1 = NULL, *bd2;
+ struct gfs2_bufdata *bd1 = NULL, *bd2, *tmp1, *tmp2;
struct page *page;
unsigned int num;
unsigned n;
@@ -661,7 +661,7 @@ static void gfs2_before_commit(struct gfs2_sbd *sdp, unsigned int limit,

gfs2_log_lock(sdp);
list_sort(NULL, blist, blocknr_cmp);
- bd1 = bd2 = list_prepare_entry(bd1, blist, bd_list);
+ tmp1 = tmp2 = list_prepare_entry(bd1, blist, bd_list);
while(total) {
num = total;
if (total > limit)
@@ -675,14 +675,18 @@ static void gfs2_before_commit(struct gfs2_sbd *sdp, unsigned int limit,
ptr = (__be64 *)(ld + 1);

n = 0;
+ bd1 = list_prepare_entry(tmp1, blist, bd_list);
+ tmp1 = NULL;
list_for_each_entry_continue(bd1, blist, bd_list) {
*ptr++ = cpu_to_be64(bd1->bd_bh->b_blocknr);
if (is_databuf) {
gfs2_check_magic(bd1->bd_bh);
*ptr++ = cpu_to_be64(buffer_escaped(bd1->bd_bh) ? 1 : 0);
}
- if (++n >= num)
+ if (++n >= num) {
+ tmp1 = bd1;
break;
+ }
}

gfs2_log_unlock(sdp);
@@ -690,6 +694,8 @@ static void gfs2_before_commit(struct gfs2_sbd *sdp, unsigned int limit,
gfs2_log_lock(sdp);

n = 0;
+ bd2 = list_prepare_entry(tmp2, blist, bd_list);
+ tmp2 = NULL;
list_for_each_entry_continue(bd2, blist, bd_list) {
get_bh(bd2->bd_bh);
gfs2_log_unlock(sdp);
@@ -712,8 +718,10 @@ static void gfs2_before_commit(struct gfs2_sbd *sdp, unsigned int limit,
gfs2_log_write_bh(sdp, bd2->bd_bh);
}
gfs2_log_lock(sdp);
- if (++n >= num)
+ if (++n >= num) {
+ tmp2 = bd2;
break;
+ }
}

BUG_ON(total < num);
base-commit: f82da161ea75dc4db21b2499e4b1facd36dab275
--
2.25.1

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