From: Yunji Kang Date: Wed, 24 Sep 2025 07:43:58 +0000 (+0900) Subject: f2fs: readahead node blocks in F2FS_GET_BLOCK_PRECACHE mode X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=72bdca6231a35aaf3fc1f3ac174d5203621d9e7f;p=thirdparty%2Fkernel%2Fstable.git f2fs: readahead node blocks in F2FS_GET_BLOCK_PRECACHE mode In f2fs_precache_extents(), For large files, It requires reading many node blocks. Instead of reading each node block with synchronous I/O, this patch applies readahead so that node blocks can be fetched in advance. It reduces the overhead of repeated sync reads and improves efficiency when precaching extents of large files. I created a file with the same largest extent and executed the test. For this experiment, I set the file's largest extent with an offset of 0 and a size of 1GB. I configured the remaining area with 100MB extents. 5GB test file: dd if=/dev/urandom of=test1 bs=1m count=5120 cp test1 test2 fsync test1 dd if=test1 of=test2 bs=1m skip=1024 seek=1024 count=100 conv=notrunc dd if=test1 of=test2 bs=1m skip=1224 seek=1224 count=100 conv=notrunc ... dd if=test1 of=test2 bs=1m skip=5024 seek=5024 count=100 conv=notrunc reboot I also created 10GB and 20GB files with large extents using the same method. ioctl(F2FS_IOC_PRECACHE_EXTENTS) test results are as follows: +-----------+---------+---------+-----------+ | File size | Before | After | Reduction | +-----------+---------+---------+-----------+ | 5GB | 101.8ms | 37.0ms | 72.1% | | 10GB | 222.9ms | 56.0ms | 74.9% | | 20GB | 446.2ms | 116.4ms | 73.9% | +-----------+---------+---------+-----------+ Tested on a 256GB mobile device with an SM8750 chipset. Reviewed-by: Sungjong Seo Reviewed-by: Sunmin Jeong Signed-off-by: Yunji Kang Reviewed-by: Chao Yu Signed-off-by: Jaegeuk Kim --- diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c index 3a974e2637aad..ed90b2c18d4c4 100644 --- a/fs/f2fs/data.c +++ b/fs/f2fs/data.c @@ -1565,6 +1565,9 @@ int f2fs_map_blocks(struct inode *inode, struct f2fs_map_blocks *map, int flag) pgofs = (pgoff_t)map->m_lblk; end = pgofs + maxblocks; + if (flag == F2FS_GET_BLOCK_PRECACHE) + mode = LOOKUP_NODE_RA; + next_dnode: if (map->m_may_create) { if (f2fs_lfs_mode(sbi))