From d860974a7e38d35e9e2c4dc8a9f4223b38b6ad99 Mon Sep 17 00:00:00 2001 From: Yeongjin Gil Date: Thu, 22 Jan 2026 19:45:27 +0900 Subject: [PATCH] f2fs: optimize f2fs_overwrite_io() for f2fs_iomap_begin When overwriting already allocated blocks, f2fs_iomap_begin() calls f2fs_overwrite_io() to check block mappings. However, f2fs_overwrite_io() iterates through all mapped blocks in the range, which can be inefficient for fragmented files with large I/O requests. This patch optimizes f2fs_overwrite_io() by adding a 'check_first' parameter and introducing __f2fs_overwrite_io() helper. When called from f2fs_iomap_begin(), we only check the first mapping to determine if the range is already allocated, which is sufficient for setting map.m_may_create. This optimization significantly reduces the number of f2fs_map_blocks() calls in f2fs_overwrite_io() when called from f2fs_iomap_begin(), especially for fragmented files with large I/O requests. Cc: stable@kernel.org Fixes: 351bc761338d ("f2fs: optimize f2fs DIO overwrites") Reviewed-by: Sungjong Seo Reviewed-by: Sunmin Jeong Signed-off-by: Yeongjin Gil Reviewed-by: Chao Yu Signed-off-by: Jaegeuk Kim --- fs/f2fs/data.c | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-) diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c index 84746a06cd58..f70efb040c73 100644 --- a/fs/f2fs/data.c +++ b/fs/f2fs/data.c @@ -1865,7 +1865,8 @@ out: return err; } -bool f2fs_overwrite_io(struct inode *inode, loff_t pos, size_t len) +static bool __f2fs_overwrite_io(struct inode *inode, loff_t pos, size_t len, + bool check_first) { struct f2fs_map_blocks map; block_t last_lblk; @@ -1887,10 +1888,17 @@ bool f2fs_overwrite_io(struct inode *inode, loff_t pos, size_t len) if (err || map.m_len == 0) return false; map.m_lblk += map.m_len; + if (check_first) + break; } return true; } +bool f2fs_overwrite_io(struct inode *inode, loff_t pos, size_t len) +{ + return __f2fs_overwrite_io(inode, pos, len, false); +} + static int f2fs_xattr_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo) { @@ -4487,7 +4495,7 @@ static int f2fs_iomap_begin(struct inode *inode, loff_t offset, loff_t length, * f2fs_map_lock and f2fs_balance_fs are not necessary. */ if ((flags & IOMAP_WRITE) && - !f2fs_overwrite_io(inode, offset, length)) + !__f2fs_overwrite_io(inode, offset, length, true)) map.m_may_create = true; err = f2fs_map_blocks(inode, &map, F2FS_GET_BLOCK_DIO); -- 2.47.3