On Mon, Apr 29, 2019 at 12:26:44PM -0500, Goldwyn Rodrigues wrote:
> From: Goldwyn Rodrigues <rgoldwyn@xxxxxxxx>
>
> With dax we cannot deal with readpage() etc. So, we create a
> funciton callback to perform the file data comparison and pass
> it to generic_remap_file_range_prep() so it can use iomap-based
> functions.
>
> This may not be the best way to solve this. Suggestions welcome.
>
> Signed-off-by: Goldwyn Rodrigues <rgoldwyn@xxxxxxxx>
> ---
> fs/btrfs/ctree.h | 9 ++++++++
> fs/btrfs/dax.c | 8 +++++++
> fs/btrfs/ioctl.c | 11 +++++++--
> fs/dax.c | 65 ++++++++++++++++++++++++++++++++++++++++++++++++++++
> fs/ocfs2/file.c | 2 +-
> fs/read_write.c | 11 +++++----
> fs/xfs/xfs_reflink.c | 2 +-
> include/linux/dax.h | 4 ++++
> include/linux/fs.h | 8 ++++++-
> 9 files changed, 110 insertions(+), 10 deletions(-)
>
> diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
> index 2b7bdabb44f8..d3d044125619 100644
> --- a/fs/btrfs/ctree.h
> +++ b/fs/btrfs/ctree.h
> @@ -3803,11 +3803,20 @@ int btree_readahead_hook(struct extent_buffer *eb, int err);
> ssize_t btrfs_file_dax_read(struct kiocb *iocb, struct iov_iter *to);
> ssize_t btrfs_file_dax_write(struct kiocb *iocb, struct iov_iter *from);
> vm_fault_t btrfs_dax_fault(struct vm_fault *vmf);
> +int btrfs_dax_file_range_compare(struct inode *src, loff_t srcoff,
> + struct inode *dest, loff_t destoff, loff_t len,
> + bool *is_same);
> #else
> static inline ssize_t btrfs_file_dax_write(struct kiocb *iocb, struct iov_iter *from)
> {
> return 0;
> }
> +static inline int btrfs_dax_file_range_compare(struct inode *src, loff_t srcoff,
> + struct inode *dest, loff_t destoff, loff_t len,
> + bool *is_same)
> +{
> + return 0;
> +}
> #endif /* CONFIG_FS_DAX */
>
> static inline int is_fstree(u64 rootid)
> diff --git a/fs/btrfs/dax.c b/fs/btrfs/dax.c
> index de957d681e16..af64696a5337 100644
> --- a/fs/btrfs/dax.c
> +++ b/fs/btrfs/dax.c
> @@ -227,4 +227,12 @@ vm_fault_t btrfs_dax_fault(struct vm_fault *vmf)
>
> return ret;
> }
> +
> +int btrfs_dax_file_range_compare(struct inode *src, loff_t srcoff,
> + struct inode *dest, loff_t destoff, loff_t len,
> + bool *is_same)
> +{
> + return dax_file_range_compare(src, srcoff, dest, destoff, len,
> + is_same, &btrfs_iomap_ops);
> +}
> #endif /* CONFIG_FS_DAX */
> diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
> index 0138119cd9a3..5ebb52848d5a 100644
> --- a/fs/btrfs/ioctl.c
> +++ b/fs/btrfs/ioctl.c
> @@ -3939,6 +3939,7 @@ static int btrfs_remap_file_range_prep(struct file *file_in, loff_t pos_in,
> bool same_inode = inode_out == inode_in;
> u64 wb_len;
> int ret;
> + compare_range_t cmp;
>
> if (!(remap_flags & REMAP_FILE_DEDUP)) {
> struct btrfs_root *root_out = BTRFS_I(inode_out)->root;
> @@ -4000,8 +4001,14 @@ static int btrfs_remap_file_range_prep(struct file *file_in, loff_t pos_in,
> if (ret < 0)
> goto out_unlock;
>
> - ret = generic_remap_file_range_prep(file_in, pos_in, file_out, pos_out,
> - len, remap_flags);
> + if (IS_DAX(file_inode(file_in)) && IS_DAX(file_inode(file_out)))
If we're moving towards a world where IS_DAX is a per-file condition, I
think this is going to need quite a bit more work to support doing
mixed-mode comparisons.
That, I think, could involve reworking vfs_dedupe_file_range_compare to
take a pair of (inode, iomap_ops) so that we can use the iomap
information to skip holes, avoid reading pages for uncached unwritten
ranges, etc.
TBH that sounds like a whole series on its own, so maybe we just want to
say no dedupe for now unless both files are in the page cache or both
files are DAX?
--D
> + cmp = btrfs_dax_file_range_compare;
> + else
> + cmp = vfs_dedupe_file_range_compare;
> +
> + ret = generic_remap_file_range_prep(file_in, pos_in, file_out,
> + pos_out, len, remap_flags, cmp);
> +
> if (ret < 0 || *len == 0)
> goto out_unlock;
>
> diff --git a/fs/dax.c b/fs/dax.c
> index 07e8ff20161d..fa9ccbad7c03 100644
> --- a/fs/dax.c
> +++ b/fs/dax.c
> @@ -39,6 +39,8 @@
> #define CREATE_TRACE_POINTS
> #include <trace/events/fs_dax.h>
>
> +#define MIN(a, b) (((a) < (b)) ? (a) : (b))
> +
> static inline unsigned int pe_order(enum page_entry_size pe_size)
> {
> if (pe_size == PE_SIZE_PTE)
> @@ -1795,3 +1797,66 @@ vm_fault_t dax_finish_sync_fault(struct vm_fault *vmf,
> return dax_insert_pfn_mkwrite(vmf, pfn, order);
> }
> EXPORT_SYMBOL_GPL(dax_finish_sync_fault);
> +
> +static inline void *iomap_address(struct iomap *iomap, loff_t off, loff_t len)
> +{
> + loff_t start;
> + void *addr;
> + start = (get_start_sect(iomap->bdev) << 9) + iomap->addr +
> + (off - iomap->offset);
> + dax_direct_access(iomap->dax_dev, PHYS_PFN(start), PHYS_PFN(len),
> + &addr, NULL);
> + return addr;
> +}
> +
> +int dax_file_range_compare(struct inode *src, loff_t srcoff, struct inode *dest,
> + loff_t destoff, loff_t len, bool *is_same, const struct iomap_ops *ops)
> +{
> + void *saddr, *daddr;
> + struct iomap s_iomap = {0};
> + struct iomap d_iomap = {0};
> + bool same = true;
> + loff_t cmp_len;
> + int id, ret = 0;
> +
> + id = dax_read_lock();
> + while (len) {
> + ret = ops->iomap_begin(src, srcoff, len, 0, &s_iomap);
> + if (ret < 0) {
> + if (ops->iomap_end)
> + ops->iomap_end(src, srcoff, len, ret, 0, &s_iomap);
> + return ret;
> + }
> + cmp_len = len;
> + cmp_len = MIN(len, s_iomap.offset + s_iomap.length - srcoff);
> +
> + ret = ops->iomap_begin(dest, destoff, cmp_len, 0, &d_iomap);
> + if (ret < 0) {
> + if (ops->iomap_end) {
> + ops->iomap_end(src, srcoff, len, ret, 0, &s_iomap);
> + ops->iomap_end(dest, destoff, len, ret, 0, &d_iomap);
> + }
> + return ret;
> + }
> + cmp_len = MIN(cmp_len, d_iomap.offset + d_iomap.length - destoff);
> +
> + saddr = iomap_address(&s_iomap, srcoff, cmp_len);
> + daddr = iomap_address(&d_iomap, destoff, cmp_len);
> +
> + same = !memcmp(saddr, daddr, cmp_len);
> + if (!same)
> + break;
> + len -= cmp_len;
> + srcoff += cmp_len;
> + destoff += cmp_len;
> +
> + if (ops->iomap_end) {
> + ret = ops->iomap_end(src, srcoff, len, 0, 0, &s_iomap);
> + ret = ops->iomap_end(dest, destoff, len, 0, 0, &d_iomap);
> + }
> + }
> + dax_read_unlock(id);
> + *is_same = same;
> + return ret;
> +}
> +EXPORT_SYMBOL_GPL(dax_file_range_compare);
> diff --git a/fs/ocfs2/file.c b/fs/ocfs2/file.c
> index d640c5f8a85d..9d470306cfc3 100644
> --- a/fs/ocfs2/file.c
> +++ b/fs/ocfs2/file.c
> @@ -2558,7 +2558,7 @@ static loff_t ocfs2_remap_file_range(struct file *file_in, loff_t pos_in,
> goto out_unlock;
>
> ret = generic_remap_file_range_prep(file_in, pos_in, file_out, pos_out,
> - &len, remap_flags);
> + &len, remap_flags, vfs_dedupe_file_range_compare);
> if (ret < 0 || len == 0)
> goto out_unlock;
>
> diff --git a/fs/read_write.c b/fs/read_write.c
> index 61b43ad7608e..c6283802ef1c 100644
> --- a/fs/read_write.c
> +++ b/fs/read_write.c
> @@ -1778,7 +1778,7 @@ static struct page *vfs_dedupe_get_page(struct inode *inode, loff_t offset)
> * Compare extents of two files to see if they are the same.
> * Caller must have locked both inodes to prevent write races.
> */
> -static int vfs_dedupe_file_range_compare(struct inode *src, loff_t srcoff,
> +int vfs_dedupe_file_range_compare(struct inode *src, loff_t srcoff,
> struct inode *dest, loff_t destoff,
> loff_t len, bool *is_same)
> {
> @@ -1845,6 +1845,7 @@ static int vfs_dedupe_file_range_compare(struct inode *src, loff_t srcoff,
> out_error:
> return error;
> }
> +EXPORT_SYMBOL_GPL(vfs_dedupe_file_range_compare);
>
> /*
> * Check that the two inodes are eligible for cloning, the ranges make
> @@ -1856,7 +1857,8 @@ static int vfs_dedupe_file_range_compare(struct inode *src, loff_t srcoff,
> */
> int generic_remap_file_range_prep(struct file *file_in, loff_t pos_in,
> struct file *file_out, loff_t pos_out,
> - loff_t *len, unsigned int remap_flags)
> + loff_t *len, unsigned int remap_flags,
> + compare_range_t compare)
> {
> struct inode *inode_in = file_inode(file_in);
> struct inode *inode_out = file_inode(file_out);
> @@ -1915,9 +1917,8 @@ int generic_remap_file_range_prep(struct file *file_in, loff_t pos_in,
> */
> if (remap_flags & REMAP_FILE_DEDUP) {
> bool is_same = false;
> -
> - ret = vfs_dedupe_file_range_compare(inode_in, pos_in,
> - inode_out, pos_out, *len, &is_same);
> + ret = (*compare)(inode_in, pos_in,
> + inode_out, pos_out, *len, &is_same);
> if (ret)
> return ret;
> if (!is_same)
> diff --git a/fs/xfs/xfs_reflink.c b/fs/xfs/xfs_reflink.c
> index 680ae7662a78..68e4257cebb0 100644
> --- a/fs/xfs/xfs_reflink.c
> +++ b/fs/xfs/xfs_reflink.c
> @@ -1350,7 +1350,7 @@ xfs_reflink_remap_prep(
> goto out_unlock;
>
> ret = generic_remap_file_range_prep(file_in, pos_in, file_out, pos_out,
> - len, remap_flags);
> + len, remap_flags, vfs_dedupe_file_range_compare);
> if (ret < 0 || *len == 0)
> goto out_unlock;
>
> diff --git a/include/linux/dax.h b/include/linux/dax.h
> index 0dd316a74a29..1370d39c91b6 100644
> --- a/include/linux/dax.h
> +++ b/include/linux/dax.h
> @@ -157,6 +157,10 @@ vm_fault_t dax_finish_sync_fault(struct vm_fault *vmf,
> int dax_delete_mapping_entry(struct address_space *mapping, pgoff_t index);
> int dax_invalidate_mapping_entry_sync(struct address_space *mapping,
> pgoff_t index);
> +int dax_file_range_compare(struct inode *src, loff_t srcoff,
> + struct inode *dest, loff_t destoff,
> + loff_t len, bool *is_same,
> + const struct iomap_ops *ops);
>
> #ifdef CONFIG_FS_DAX
> int __dax_zero_page_range(struct block_device *bdev,
> diff --git a/include/linux/fs.h b/include/linux/fs.h
> index dd28e7679089..0224503e42ce 100644
> --- a/include/linux/fs.h
> +++ b/include/linux/fs.h
> @@ -1883,10 +1883,16 @@ extern ssize_t vfs_readv(struct file *, const struct iovec __user *,
> unsigned long, loff_t *, rwf_t);
> extern ssize_t vfs_copy_file_range(struct file *, loff_t , struct file *,
> loff_t, size_t, unsigned int);
> +extern int vfs_dedupe_file_range_compare(struct inode *src, loff_t srcoff,
> + struct inode *dest, loff_t destoff,
> + loff_t len, bool *is_same);
> +typedef int (*compare_range_t)(struct inode *src, loff_t srcpos,
> + struct inode *dest, loff_t destpos,
> + loff_t len, bool *is_same);
> extern int generic_remap_file_range_prep(struct file *file_in, loff_t pos_in,
> struct file *file_out, loff_t pos_out,
> loff_t *count,
> - unsigned int remap_flags);
> + unsigned int remap_flags, compare_range_t cmp);
> extern loff_t do_clone_file_range(struct file *file_in, loff_t pos_in,
> struct file *file_out, loff_t pos_out,
> loff_t len, unsigned int remap_flags);
> --
> 2.16.4
>
