Subsequent deallocation of newly allocated padding blocks is ensured by
writing the actual discarded extents back to the discard set.
Signed-off-by: Ivan Shapovalov <intelfx100@xxxxxxxxx>
---
fs/reiser4/discard.c | 50 ++++++++++++++++++++++++++++++++++++++++++++------
1 file changed, 44 insertions(+), 6 deletions(-)
diff --git a/fs/reiser4/discard.c b/fs/reiser4/discard.c
index 86ff6e4..68865d2 100644
--- a/fs/reiser4/discard.c
+++ b/fs/reiser4/discard.c
@@ -221,7 +221,15 @@ static inline struct list_head *get_next_at(struct list_head *pos,
static inline int check_free_blocks(const reiser4_block_nr start,
const reiser4_block_nr len)
{
- return reiser4_check_blocks(&start, &len, 0);
+ /*
+ * NOTE: we do not use BA_PERMANENT in out allocations
+ * even though these blocks are later deallocated with BA_DEFER
+ * (via updating the delete set with newly allocated blocks).
+ * The discard code is ran after the pre-commit hook so deallocated block
+ * accounting is already done.
+ */
+ return reiser4_alloc_blocks_exact (&start, &len, BLOCK_NOT_COUNTED,
+ BA_FORMATTED) == 0;
}
/* Make sure that extents are sorted and merged */
@@ -255,6 +263,8 @@ static inline void check_blocknr_list_at(struct list_head *pos,
* extent in the working space map. Try to "glue" the nearby
* extents. Discard the (glued) extents with padded (or cut)
* head and tail.
+ * The paddings, if any, are allocated before discarding, and the list
+ * is updated to contain all new allocations.
*
* Pre-conditions: @head points to the list of sorted and
* merged extents.
@@ -274,6 +284,9 @@ static inline void check_blocknr_list_at(struct list_head *pos,
* astart - actual start to discard (offset of the head padding);
* alen - actual length to discard (length of glued aligned and padded extents).
*
+ * estart - start of extent to be written back to the list
+ * eend - end (last block + 1) of extent to be written back to the list
+ *
* Terminology in the comments:
*
* head - a part of extent at the beginning;
@@ -299,11 +312,14 @@ static int discard_sorted_merged_extents(struct list_head *head)
reiser4_block_nr len;
reiser4_block_nr end;
reiser4_block_nr astart; __s64 alen;
+ reiser4_block_nr estart, eend;
check_blocknr_list_at(pos, head);
start = blocknr_list_entry_start(pos);
len = blocknr_list_entry_len(pos);
+ estart = start;
+
/*
* Step I. Cut or pad the head of extent
*
@@ -326,6 +342,7 @@ static int discard_sorted_merged_extents(struct list_head *head)
*/
astart = start - headp;
alen = len + headp;
+ estart -= headp;
} else {
/*
* head padding is dirty,
@@ -341,10 +358,11 @@ static int discard_sorted_merged_extents(struct list_head *head)
* Cut or pad the tail of the last extent.
*/
end = start + len;
+ eend = end;
tailp = extent_get_tailp(end, d_off, d_uni);
/*
- * This "gluing" loop updates @pos, @end, @tailp, @alen
+ * This "gluing" loop updates @end, @tailp, @alen, @eend
*/
while (1) {
struct list_head *next;
@@ -366,10 +384,17 @@ static int discard_sorted_merged_extents(struct list_head *head)
/*
* jump to the glued extent
*/
- pos = next;
alen += (next_start + next_len - end);
end = next_start + next_len;
tailp = extent_get_tailp(end, d_off, d_uni);
+ eend = end;
+ /*
+ * remove the glued extent from the list
+ *
+ * (don't update pos, current next->next
+ * will become pos->next)
+ */
+ blocknr_list_del(next);
/*
* try to glue more extents
*/
@@ -395,13 +420,14 @@ static int discard_sorted_merged_extents(struct list_head *head)
*/
if (tailp == 0)
break;
- else if (check_free_blocks(end, tailp))
+ else if (check_free_blocks(end, tailp)) {
/*
* tail padding is clean,
* pad the tail
*/
alen += tailp;
- else
+ eend += tailp;
+ } else
/*
* tail padding is dirty,
* cut the tail
@@ -415,6 +441,18 @@ static int discard_sorted_merged_extents(struct list_head *head)
* Step III. Discard the result
*/
if (alen > 0) {
+ assert("intelfx-74", estart < eend);
+ assert("intelfx-75", estart <= start);
+ assert("intelfx-76", estart <= astart);
+ assert("intelfx-77", start + len <= eend);
+ assert("intelfx-78", astart + alen <= eend);
+
+ /* here @eend becomes length */
+ eend -= estart;
+ assert("intelfx-79",
+ reiser4_check_blocks(&estart, &eend, 1));
+ blocknr_list_update_extent(pos, &estart, &eend);
+
ret = __discard_extent(sb->s_bdev,
astart * (sb->s_blocksize >> 9),
alen * (sb->s_blocksize >> 9));
@@ -453,7 +491,7 @@ int discard_atom(txn_atom *atom, struct list_head *processed_set)
/* Sort the discard list, joining adjacent and overlapping extents. */
blocknr_list_sort_and_join(&discard_set);
- /* Perform actual dirty work. */
+ /* Perform actual dirty work. The discard set may change at this point. */
ret = discard_sorted_merged_extents(&discard_set);
/* Add processed extents to the temporary list. */
--
2.1.3
--
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