From 7ed6cbe0f8caa6ee38a2dc8f1b925acb904cc01f Mon Sep 17 00:00:00 2001 From: Christoph Hellwig Date: Thu, 9 Jan 2025 09:31:02 +0100 Subject: [PATCH] fs: add STATX_DIO_READ_ALIGN Add a separate dio read align field, as many out of place write file systems can easily do reads aligned to the device sector size, but require bigger alignment for writes. This is usually papered over by falling back to buffered I/O for smaller writes and doing read-modify-write cycles, but performance for this sucks, so applications benefit from knowing the actual write alignment. Signed-off-by: Christoph Hellwig Link: https://lore.kernel.org/r/20250109083109.1441561-3-hch@lst.de Reviewed-by: John Garry Reviewed-by: Jan Kara Reviewed-by: Darrick J. Wong Signed-off-by: Christian Brauner --- fs/stat.c | 1 + include/linux/stat.h | 1 + include/uapi/linux/stat.h | 4 +++- 3 files changed, 5 insertions(+), 1 deletion(-) diff --git a/fs/stat.c b/fs/stat.c index 0870e969a8a0b..2c0e111a098a1 100644 --- a/fs/stat.c +++ b/fs/stat.c @@ -725,6 +725,7 @@ cp_statx(const struct kstat *stat, struct statx __user *buffer) tmp.stx_mnt_id = stat->mnt_id; tmp.stx_dio_mem_align = stat->dio_mem_align; tmp.stx_dio_offset_align = stat->dio_offset_align; + tmp.stx_dio_read_offset_align = stat->dio_read_offset_align; tmp.stx_subvol = stat->subvol; tmp.stx_atomic_write_unit_min = stat->atomic_write_unit_min; tmp.stx_atomic_write_unit_max = stat->atomic_write_unit_max; diff --git a/include/linux/stat.h b/include/linux/stat.h index 3d900c86981c5..9d8382e23a9c6 100644 --- a/include/linux/stat.h +++ b/include/linux/stat.h @@ -52,6 +52,7 @@ struct kstat { u64 mnt_id; u32 dio_mem_align; u32 dio_offset_align; + u32 dio_read_offset_align; u64 change_cookie; u64 subvol; u32 atomic_write_unit_min; diff --git a/include/uapi/linux/stat.h b/include/uapi/linux/stat.h index 8b35d7d511a28..f78ee3670dd5d 100644 --- a/include/uapi/linux/stat.h +++ b/include/uapi/linux/stat.h @@ -179,7 +179,8 @@ struct statx { /* Max atomic write segment count */ __u32 stx_atomic_write_segments_max; - __u32 __spare1[1]; + /* File offset alignment for direct I/O reads */ + __u32 stx_dio_read_offset_align; /* 0xb8 */ __u64 __spare3[9]; /* Spare space for future expansion */ @@ -213,6 +214,7 @@ struct statx { #define STATX_MNT_ID_UNIQUE 0x00004000U /* Want/got extended stx_mount_id */ #define STATX_SUBVOL 0x00008000U /* Want/got stx_subvol */ #define STATX_WRITE_ATOMIC 0x00010000U /* Want/got atomic_write_* fields */ +#define STATX_DIO_READ_ALIGN 0x00020000U /* Want/got dio read alignment info */ #define STATX__RESERVED 0x80000000U /* Reserved for future struct statx expansion */ -- 2.39.5