man/man2/statx.2: Document STATX_DIO_READ_ALIGN

Document the new STATX_DIO_READ_ALIGN flag and the new
stx_dio_read_offset_align field guarded by it.

Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Jan Kara <jack@suse.cz>
Cc: Chandan Babu R <chandan.babu@oracle.com>
Cc: Hongbo Li <lihongbo22@huawei.com>
Cc: Ryusuke Konishi <konishi.ryusuke@gmail.com>
Cc: <linux-nilfs@vger.kernel.org>
Cc: <linux-fsdevel@vger.kernel.org>
Cc: <linux-xfs@vger.kernel.org>
Reviewed-by: "Darrick J. Wong" <djwong@kernel.org>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Message-ID: <20250109083226.GA22264@lst.de>
Signed-off-by: Alejandro Colomar <alx@kernel.org>

diff --git a/man/man2/statx.2 b/man/man2/statx.2
index 7fab1d3d844103038695af39ee99a96c917eb275..0abac75c1837d456adb15c0de15a033cc9094060 100644 (file)
--- a/man/man2/statx.2
+++ b/man/man2/statx.2
@@ -76,6 +76,9 @@ struct statx {
     __u32 stx_atomic_write_unit_min;
     __u32 stx_atomic_write_unit_max;
     __u32 stx_atomic_write_segments_max;
+\&
+    /* File offset alignment for direct I/O reads */
+    __u32   stx_dio_read_offset_align;
 };
 .EE
 .in
@@ -261,7 +264,7 @@ STATX_BTIME Want stx_btime
 STATX_ALL      The same as STATX_BASIC_STATS | STATX_BTIME.
        It is deprecated and should not be used.
 STATX_MNT_ID   Want stx_mnt_id (since Linux 5.8)
-STATX_DIOALIGN Want stx_dio_mem_align and stx_dio_offset_align
+STATX_DIOALIGN Want stx_dio_mem_align and stx_dio_offset_align.
        (since Linux 6.1; support varies by filesystem)
 STATX_MNT_ID_UNIQUE    Want unique stx_mnt_id (since Linux 6.8)
 STATX_SUBVOL   Want stx_subvol
@@ -270,6 +273,8 @@ STATX_WRITE_ATOMIC  Want stx_atomic_write_unit_min,
        stx_atomic_write_unit_max,
        and stx_atomic_write_segments_max.
        (since Linux 6.11; support varies by filesystem)
+STATX_DIO_READ_ALIGN   Want stx_dio_read_offset_align.
+       (since Linux 6.14; support varies by filesystem)
 .TE
 .in
 .P
@@ -467,6 +472,28 @@ This will only be nonzero if
 .I stx_dio_mem_align
 is nonzero, and vice versa.
 .TP
+.I stx_dio_read_offset_align
+The alignment (in bytes) required for file offsets and I/O segment lengths for
+direct I/O reads
+.RB ( O_DIRECT )
+on this file.
+If zero,
+the limit in
+.I stx_dio_offset_align
+applies for reads as well.
+If non-zero,
+this value must be smaller than or equal to
+.I stx_dio_offset_align
+which must be provided by the file system
+if requested by the application.
+The memory alignment in
+.I stx_dio_mem_align
+is not affected by this value.
+.IP
+.B STATX_DIO_READ_ALIGN
+.RI ( stx_dio_offset_align )
+is supported by xfs on regular files since Linux 6.14.
+.TP
 .I stx_subvol
 Subvolume number of the current file.
 .IP