f2fs: add a tracepoint to see large folio read submission

f2fs: add a tracepoint to see large folio read submission

For example,

1327.539878: f2fs_preload_pages_start: dev = (252,16), ino = 14, i_size = 4294967296 start: 0, end: 8191
1327.539878: page_cache_sync_ra: dev=252:16 ino=e index=0 req_count=8192 order=9 size=0 async_size=0 ra_pages=4096 mmap_miss=0 prev_pos=-1
1327.539879: page_cache_ra_order: dev=252:16 ino=e index=0 order=9 size=4096 async_size=2048 ra_pages=4096
1327.541895: f2fs_readpages: dev = (252,16), ino = 14, start = 0 nrpage = 4096
1327.541930: f2fs_lookup_extent_tree_start: dev = (252,16), ino = 14, pgofs = 0, type = Read
1327.541931: f2fs_lookup_read_extent_tree_end: dev = (252,16), ino = 14, pgofs = 0, read_ext_info(fofs: 0, len: 1048576, blk: 4221440)
1327.541931: f2fs_map_blocks: dev = (252,16), ino = 14, file offset = 0, start blkaddr = 0x406a00, len = 0x1000, flags = 2, seg_type = 8, may_create = 0, multidevice = 0, flag = 0, err = 0
1327.541989: f2fs_read_folio: dev = (252,16), ino = 14, DATA, FILE, index = 0, nr_pages = 512, dirty = 0, uptodate = 0
1327.542012: f2fs_read_folio: dev = (252,16), ino = 14, DATA, FILE, index = 512, nr_pages = 512, dirty = 0, uptodate = 0
1327.542036: f2fs_read_folio: dev = (252,16), ino = 14, DATA, FILE, index = 1024, nr_pages = 512, dirty = 0, uptodate = 0
1327.542080: f2fs_read_folio: dev = (252,16), ino = 14, DATA, FILE, index = 1536, nr_pages = 512, dirty = 0, uptodate = 0
1327.542127: f2fs_read_folio: dev = (252,16), ino = 14, DATA, FILE, index = 2048, nr_pages = 512, dirty = 0, uptodate = 0
1327.542151: f2fs_read_folio: dev = (252,16), ino = 14, DATA, FILE, index = 2560, nr_pages = 512, dirty = 0, uptodate = 0
1327.542196: f2fs_read_folio: dev = (252,16), ino = 14, DATA, FILE, index = 3072, nr_pages = 512, dirty = 0, uptodate = 0
1327.542219: f2fs_read_folio: dev = (252,16), ino = 14, DATA, FILE, index = 3584, nr_pages = 512, dirty = 0, uptodate = 0
1327.542239: f2fs_submit_read_bio: dev = (252,16)/(252,16), rw = READ(R), DATA, sector = 33771520, size = 16777216
1327.542269: page_cache_sync_ra: dev=252:16 ino=e index=4096 req_count=8192 order=9 size=4096 async_size=2048 ra_pages=4096 mmap_miss=0 prev_pos=-1
1327.542289: page_cache_ra_order: dev=252:16 ino=e index=4096 order=9 size=4096 async_size=2048 ra_pages=4096
1327.544485: f2fs_readpages: dev = (252,16), ino = 14, start = 4096 nrpage = 4096
1327.544521: f2fs_lookup_extent_tree_start: dev = (252,16), ino = 14, pgofs = 4096, type = Read
1327.544521: f2fs_lookup_read_extent_tree_end: dev = (252,16), ino = 14, pgofs = 4096, read_ext_info(fofs: 0, len: 1048576, blk: 4221440)
1327.544522: f2fs_map_blocks: dev = (252,16), ino = 14, file offset = 4096, start blkaddr = 0x407a00, len = 0x1000, flags = 2, seg_type = 8, may_create = 0, multidevice = 0, flag = 0, err = 0
1327.544550: f2fs_read_folio: dev = (252,16), ino = 14, DATA, FILE, index = 4096, nr_pages = 512, dirty = 0, uptodate = 0
1327.544575: f2fs_read_folio: dev = (252,16), ino = 14, DATA, FILE, index = 4608, nr_pages = 512, dirty = 0, uptodate = 0
1327.544601: f2fs_read_folio: dev = (252,16), ino = 14, DATA, FILE, index = 5120, nr_pages = 512, dirty = 0, uptodate = 0
1327.544647: f2fs_read_folio: dev = (252,16), ino = 14, DATA, FILE, index = 5632, nr_pages = 512, dirty = 0, uptodate = 0
1327.544692: f2fs_read_folio: dev = (252,16), ino = 14, DATA, FILE, index = 6144, nr_pages = 512, dirty = 0, uptodate = 0
1327.544734: f2fs_read_folio: dev = (252,16), ino = 14, DATA, FILE, index = 6656, nr_pages = 512, dirty = 0, uptodate = 0
1327.544777: f2fs_read_folio: dev = (252,16), ino = 14, DATA, FILE, index = 7168, nr_pages = 512, dirty = 0, uptodate = 0
1327.544805: f2fs_read_folio: dev = (252,16), ino = 14, DATA, FILE, index = 7680, nr_pages = 512, dirty = 0, uptodate = 0
1327.544826: f2fs_submit_read_bio: dev = (252,16)/(252,16), rw = READ(R), DATA, sector = 33804288, size = 16777216
1327.544852: f2fs_preload_pages_end: dev = (252,16), ino = 14, i_size = 4294967296 start: 8192, end: 8191

Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>