From: Yongpeng Yang <[email protected]> After the device is mounted, f2fs updates on-disk metadata without updating the block device page cache. As a result, f2fs-tools may read stale metadata from the page cache.
For example: mount /dev/vdb /mnt/f2fs touch mx // ino = 4 sync dump.f2fs -i 4 /dev/vdb touch mx2 // ino = 5 sync dump.f2fs -i 5 /dev/vdb // block addr is 0 Since `dump.f2fs -i 4 /dev/vdb` has already populated the metadata area into the block device page cache, the cached pages remain resident in memory. After creating mx2, the page cache is not updated accordingly. Therefore, `dump.f2fs -i 5 /dev/vdb` reads stale metadata, and the physical block address of inode 5 is incorrectly reported as 0. This patch issues a BLKFLSBUF ioctl to the block device before reading metadata. The kernel then invalidates the block device page cache, ensuring that subsequent reads fetch uptodate metadata from disk. Signed-off-by: Yongpeng Yang <[email protected]> --- lib/libf2fs.c | 1 + 1 file changed, 1 insertion(+) diff --git a/lib/libf2fs.c b/lib/libf2fs.c index 1a496b7..31b5924 100644 --- a/lib/libf2fs.c +++ b/lib/libf2fs.c @@ -1027,6 +1027,7 @@ int get_device_info(int i) } dev->fd = fd; + ioctl(fd, BLKFLSBUF); if (c.sparse_mode && i == 0) { if (f2fs_init_sparse_file()) { -- 2.52.0 _______________________________________________ Linux-f2fs-devel mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel
