[PATCH v4 00/11] exfat: convert to iomap

[Namjae Jeon <linkinjeon@kernel.org>]

This patch series converts the exfat filesystem to the iomap framework for
buffered I/O, direct I/O, and llseek (SEEK_HOLE/SEEK_DATA) support.

iozone benchmark results (4KB cluster size, -s1g -r64k, 1GB file, 64KB record size)

                       1 thread                  4 threads
                     Write      Read           Write      Read
                     (MB/s)    (MB/s)         (MB/s)    (MB/s)
-----------------------------------------------------------------
exfat + iomap patch   332.7     418.1           78.6      82.4
Current exfat         278.4     415.1           42.1      38.0
-----------------------------------------------------------------
Improvement           +19.5%    +0.7%          +86.7%   +117.4%


Available in the Git repository at:
===================================
git://git.kernel.org/pub/scm/linux/kernel/git/linkinjeon/exfat.git iomap-work

v4:
  - Declare initialized variables before uninitialized ones in
    __iomap_write_begin.
  - Clean up the logic for handling ei->valid_size in the non-alloc
    iomap read path.
  - Rename exfat_cluster_to_phys to exfat_cluster_to_phys_bytes.
  - Use end variable in exfat_fallback_buffered_write.

v3:
  - Remove extra >> 9 when adding to inode->i_blocks.
  - Simplify exfat_file_open() by removing unnecessary err variable.
  - Separate exfat_truncate() error return conversion from iomap changes.
  - Fix xfstests failures with 512B cluster size.
  - Make exfat_truncate() return error code.
  - Use inode lock to protect valid_size in exfat_extend_valid_size().
  - Unify num_clusters calculation regardless of may_alloc.
  - Use min_t() to clamp iomap->length.
  - Return early in exfat_write_iomap_end() if no data written.
  - Remove s_lock in exfat_write_iomap_end().
  - Split DIO fallback buffered write into helper function.
  - Remove unnecessary goto in exfat_dio_write_iter().

v2:
  - Replace macros with static inline functions.
  - Remove noop_direct_IO.
  - Consolidate read and write iomap_begin into __exfat_iomap_begin()
  - Zero out stale data in straddle block beyond valid_size.
  - Introduce IOMAP_F_ZERO_TAIL flag to remove exfat_iomap_put_folio().
  - Select FS_IOMAP in Kconfig.
  - Remove unnecessary alignment check in exfat_file_read_iter().
  - Just use generic_file_llseek directly.
  - Move exfat_extend_valid_size to exfat_file_write_iter().
  - Use pagecache_isize_extended() to remove iomap_zero_range in
    exfat_setattr().
  - fix mmap write data corruption with byte-by-byte fallocate.
  - Remove exfat_mkwrite_iomap_begin().

Namjae Jeon (11):
  iomap: introduce IOMAP_F_ZERO_TAIL flag
  exfat: replace unsafe macros with static inline functions
  exfat: add balloc parameter to exfat_map_cluster() for iomap support
  exfat: add exfat_file_open()
  exfat: add support for multi-cluster allocation
  exfat: add data_start_bytes and exfat_cluster_to_phys_bytes() helper
  exfat: fix implicit declaration of brelse()
  exfat: add iomap buffered I/O support
  exfat: add iomap direct I/O support
  exfat: add support for SEEK_HOLE and SEEK_DATA in llseek
  exfat: make exfat_truncate() return error code

 fs/exfat/Kconfig       |   2 +-
 fs/exfat/Makefile      |   2 +-
 fs/exfat/balloc.c      |   2 +-
 fs/exfat/dir.c         |  50 +++---
 fs/exfat/exfat_fs.h    | 140 ++++++++++++-----
 fs/exfat/fatent.c      |  30 ++--
 fs/exfat/file.c        | 263 +++++++++++++++++++++++--------
 fs/exfat/inode.c       | 342 ++++++-----------------------------------
 fs/exfat/iomap.c       | 263 +++++++++++++++++++++++++++++++
 fs/exfat/iomap.h       |  15 ++
 fs/exfat/namei.c       |  28 ++--
 fs/exfat/super.c       |   5 +-
 fs/iomap/buffered-io.c |   4 +
 include/linux/iomap.h  |   4 +
 14 files changed, 703 insertions(+), 447 deletions(-)
 create mode 100644 fs/exfat/iomap.c
 create mode 100644 fs/exfat/iomap.h

-- 
2.25.1