From: Eric Biggers <ebigg...@google.com>

Add support for STATX_IOALIGN to f2fs, so that I/O alignment information
is exposed to userspace in a consistent and easy-to-use way.

Signed-off-by: Eric Biggers <ebigg...@google.com>
---
 fs/f2fs/file.c | 31 +++++++++++++++++++++++++++++++
 1 file changed, 31 insertions(+)

diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
index c32f7722ba6b0..f89a190949c59 100644
--- a/fs/f2fs/file.c
+++ b/fs/f2fs/file.c
@@ -835,6 +835,21 @@ static bool f2fs_force_buffered_io(struct inode *inode)
        return false;
 }
 
+/* Return the maximum value of io_opt across all the filesystem's devices. */
+static unsigned int f2fs_max_io_opt(struct inode *inode)
+{
+       struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
+       int io_opt = 0;
+       int i;
+
+       if (!f2fs_is_multi_device(sbi))
+               return bdev_io_opt(sbi->sb->s_bdev);
+
+       for (i = 0; i < sbi->s_ndevs; i++)
+               io_opt = max(io_opt, bdev_io_opt(FDEV(i).bdev));
+       return io_opt;
+}
+
 int f2fs_getattr(struct user_namespace *mnt_userns, const struct path *path,
                 struct kstat *stat, u32 request_mask, unsigned int query_flags)
 {
@@ -851,6 +866,22 @@ int f2fs_getattr(struct user_namespace *mnt_userns, const 
struct path *path,
                stat->btime.tv_nsec = fi->i_crtime.tv_nsec;
        }
 
+       /*
+        * Return the I/O alignment information if requested.  We only return
+        * this information when requested, since on encrypted files it might
+        * take a fair bit of work to get if the file wasn't opened recently.
+        */
+       if ((request_mask & STATX_IOALIGN) && S_ISREG(inode->i_mode)) {
+               unsigned int bsize = i_blocksize(inode);
+
+               stat->result_mask |= STATX_IOALIGN;
+               if (!f2fs_force_buffered_io(inode)) {
+                       stat->mem_align_dio = bsize;
+                       stat->offset_align_dio = bsize;
+               }
+               stat->offset_align_optimal = max(f2fs_max_io_opt(inode), bsize);
+       }
+
        flags = fi->i_flags;
        if (flags & F2FS_COMPR_FL)
                stat->attributes |= STATX_ATTR_COMPRESSED;
-- 
2.36.1



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