Hi Chao:
On 2026/1/12 09:33, Chao Yu via Linux-f2fs-devel wrote:
For consecutive large hole mapping across {d,id,did}nodes , we don't
need to call f2fs_map_blocks() to check one hole block per one time,
instead, we can use map.m_next_pgofs as a hint of next potential valid
block, so that we can skip calling f2fs_map_blocks the range of
[cur_pgofs + 1, .m_next_pgofs).
1) regular case
touch /mnt/f2fs/file
truncate -s $((1024*1024*1024)) /mnt/f2fs/file
time dd if=/mnt/f2fs/file of=/dev/null bs=1M count=1024
Before:
real 0m0.706s
user 0m0.000s
sys 0m0.706s
After:
real 0m0.620s
user 0m0.008s
sys 0m0.611s
2) large folio case
touch /mnt/f2fs/file
truncate -s $((1024*1024*1024)) /mnt/f2fs/file
f2fs_io setflags immutable /mnt/f2fs/file
sync
echo 3 > /proc/sys/vm/drop_caches
time dd if=/mnt/f2fs/file of=/dev/null bs=1M count=1024
Before:
real 0m0.438s
user 0m0.004s
sys 0m0.433s
After:
real 0m0.368s
user 0m0.004s
sys 0m0.364s
Signed-off-by: Chao Yu <[email protected]>
---
fs/f2fs/data.c | 21 +++++++++++++++------
1 file changed, 15 insertions(+), 6 deletions(-)
diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
index a2c4769d0ae1..5b0642cd27ff 100644
--- a/fs/f2fs/data.c
+++ b/fs/f2fs/data.c
@@ -2176,10 +2176,13 @@ static int f2fs_read_single_page(struct inode *inode,
struct folio *folio,
/*
* Map blocks using the previous result first.
*/
- if ((map->m_flags & F2FS_MAP_MAPPED) &&
- block_in_file > map->m_lblk &&
+ if (map->m_flags & F2FS_MAP_MAPPED) {
+ if (block_in_file > map->m_lblk &&
block_in_file < (map->m_lblk + map->m_len))
+ goto got_it;
+ } else if (block_in_file < *map->m_next_pgofs) {
goto got_it;
+ }
/*
* Then do more f2fs_map_blocks() calls until we are
@@ -2454,7 +2457,7 @@ static int f2fs_read_data_large_folio(struct inode *inode,
struct bio *bio = NULL;
sector_t last_block_in_bio = 0;
struct f2fs_map_blocks map = {0, };
- pgoff_t index, offset;
+ pgoff_t index, offset, next_pgofs = 0;
unsigned max_nr_pages = rac ? readahead_count(rac) :
folio_nr_pages(folio);
unsigned nrpages;
@@ -2487,16 +2490,21 @@ static int f2fs_read_data_large_folio(struct inode
*inode,
/*
* Map blocks using the previous result first.
*/
- if ((map.m_flags & F2FS_MAP_MAPPED) &&
- index > map.m_lblk &&
+ if (map.m_flags & F2FS_MAP_MAPPED) {
+ if (index > map.m_lblk &&
index < (map.m_lblk + map.m_len))
+ goto got_it;
+ } else if (index < next_pgofs) {
+ /* hole case */
goto got_it;
+ }
/*
* Then do more f2fs_map_blocks() calls until we are
* done with this page.
*/
memset(&map, 0, sizeof(map));
+ map.m_next_pgofs = &next_pgofs;
map.m_seg_type = NO_CHECK_TYPE;
map.m_lblk = index;
map.m_len = max_nr_pages;
@@ -2617,6 +2625,7 @@ static int f2fs_mpage_readpages(struct inode *inode,
pgoff_t nc_cluster_idx = NULL_CLUSTER;
pgoff_t index;
#endif
+ pgoff_t next_pgofs = 0;
unsigned nr_pages = rac ? readahead_count(rac) : 1;
struct address_space *mapping = rac ? rac->mapping : folio->mapping;
unsigned max_nr_pages = nr_pages;
@@ -2637,7 +2646,7 @@ static int f2fs_mpage_readpages(struct inode *inode,
map.m_lblk = 0;
map.m_len = 0;
map.m_flags = 0;
- map.m_next_pgofs = NULL;
+ map.m_next_pgofs = &next_pgofs;
map.m_next_extent = NULL;
map.m_seg_type = NO_CHECK_TYPE;
map.m_may_create = false;
Do we have plans to also support reducing f2fs_map_blocks() calls for
consectives holes in logical file postion with dnode have already been
allocated in buffered large folio read?
Such as consective NULL_ADDR or NEW_ADDR?
Thanks,
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