[RFC PATCH v2 7/7] f2fs: support STATX_IOALIGN

Eric Biggers
2022-05-18T23:54:17Z

From: Eric Biggers <ebiggers@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 <ebiggers@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