[PATCH 17/28] vfs: hide file range comparison function

Darrick J. Wong
2018-10-22T00:34:07Z

There are no callers of vfs_dedupe_file_range_compare, so we might as
well make it a static helper and remove the export.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
---
fs/read_write.c | 187 +++++++++++++++++++++++++---------------------------
include/linux/fs.h | 3 -
2 files changed, 91 insertions(+), 99 deletions(-)

diff --git a/fs/read_write.c b/fs/read_write.c
index c0bcc1a20650..e4d295d0d236 100644
--- a/fs/read_write.c
+++ b/fs/read_write.c
@@ -1752,6 +1752,97 @@ static int generic_remap_check_len(struct inode *inode_in,
return (remap_flags & REMAP_FILE_DEDUP) ? -EBADE : -EINVAL;
}

+/*
+ * Read a page's worth of file data into the page cache. Return the page
+ * locked.
+ */
+static struct page *vfs_dedupe_get_page(struct inode *inode, loff_t offset)
+{
+ struct page *page;
+
+ page = read_mapping_page(inode->i_mapping, offset >> PAGE_SHIFT, NULL);
+ if (IS_ERR(page))
+ return page;
+ if (!PageUptodate(page)) {
+ put_page(page);
+ return ERR_PTR(-EIO);
+ }
+ lock_page(page);
+ return page;
+}
+
+/*
+ * 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,
+ struct inode *dest, loff_t destoff,
+ loff_t len, bool *is_same)
+{
+ loff_t src_poff;
+ loff_t dest_poff;
+ void *src_addr;
+ void *dest_addr;
+ struct page *src_page;
+ struct page *dest_page;
+ loff_t cmp_len;
+ bool same;
+ int error;
+
+ error = -EINVAL;
+ same = true;
+ while (len) {
+ src_poff = srcoff & (PAGE_SIZE - 1);
+ dest_poff = destoff & (PAGE_SIZE - 1);
+ cmp_len = min(PAGE_SIZE - src_poff,
+ PAGE_SIZE - dest_poff);
+ cmp_len = min(cmp_len, len);
+ if (cmp_len <= 0)
+ goto out_error;
+
+ src_page = vfs_dedupe_get_page(src, srcoff);
+ if (IS_ERR(src_page)) {
+ error = PTR_ERR(src_page);
+ goto out_error;
+ }
+ dest_page = vfs_dedupe_get_page(dest, destoff);
+ if (IS_ERR(dest_page)) {
+ error = PTR_ERR(dest_page);
+ unlock_page(src_page);
+ put_page(src_page);
+ goto out_error;
+ }
+ src_addr = kmap_atomic(src_page);
+ dest_addr = kmap_atomic(dest_page);
+
+ flush_dcache_page(src_page);
+ flush_dcache_page(dest_page);
+
+ if (memcmp(src_addr + src_poff, dest_addr + dest_poff, cmp_len))
+ same = false;
+
+ kunmap_atomic(dest_addr);
+ kunmap_atomic(src_addr);
+ unlock_page(dest_page);
+ unlock_page(src_page);
+ put_page(dest_page);
+ put_page(src_page);
+
+ if (!same)
+ break;
+
+ srcoff += cmp_len;
+ destoff += cmp_len;
+ len -= cmp_len;
+ }
+
+ *is_same = same;
+ return 0;
+
+out_error:
+ return error;
+}
+
/*
* Check that the two inodes are eligible for cloning, the ranges make
* sense, and then flush all dirty data. Caller must ensure that the
@@ -1923,102 +2014,6 @@ loff_t vfs_clone_file_range(struct file *file_in, loff_t pos_in,
}
EXPORT_SYMBOL(vfs_clone_file_range);

-/*
- * Read a page's worth of file data into the page cache. Return the page
- * locked.
- */
-static struct page *vfs_dedupe_get_page(struct inode *inode, loff_t offset)
-{
- struct address_space *mapping;
- struct page *page;
- pgoff_t n;
-
- n = offset >> PAGE_SHIFT;
- mapping = inode->i_mapping;
- page = read_mapping_page(mapping, n, NULL);
- if (IS_ERR(page))
- return page;
- if (!PageUptodate(page)) {
- put_page(page);
- return ERR_PTR(-EIO);
- }
- lock_page(page);
- return page;
-}
-
-/*
- * Compare extents of two files to see if they are the same.
- * Caller must have locked both inodes to prevent write races.
- */
-int vfs_dedupe_file_range_compare(struct inode *src, loff_t srcoff,
- struct inode *dest, loff_t destoff,
- loff_t len, bool *is_same)
-{
- loff_t src_poff;
- loff_t dest_poff;
- void *src_addr;
- void *dest_addr;
- struct page *src_page;
- struct page *dest_page;
- loff_t cmp_len;
- bool same;
- int error;
-
- error = -EINVAL;
- same = true;
- while (len) {
- src_poff = srcoff & (PAGE_SIZE - 1);
- dest_poff = destoff & (PAGE_SIZE - 1);
- cmp_len = min(PAGE_SIZE - src_poff,
- PAGE_SIZE - dest_poff);
- cmp_len = min(cmp_len, len);
- if (cmp_len <= 0)
- goto out_error;
-
- src_page = vfs_dedupe_get_page(src, srcoff);
- if (IS_ERR(src_page)) {
- error = PTR_ERR(src_page);
- goto out_error;
- }
- dest_page = vfs_dedupe_get_page(dest, destoff);
- if (IS_ERR(dest_page)) {
- error = PTR_ERR(dest_page);
- unlock_page(src_page);
- put_page(src_page);
- goto out_error;
- }
- src_addr = kmap_atomic(src_page);
- dest_addr = kmap_atomic(dest_page);
-
- flush_dcache_page(src_page);
- flush_dcache_page(dest_page);
-
- if (memcmp(src_addr + src_poff, dest_addr + dest_poff, cmp_len))
- same = false;
-
- kunmap_atomic(dest_addr);
- kunmap_atomic(src_addr);
- unlock_page(dest_page);
- unlock_page(src_page);
- put_page(dest_page);
- put_page(src_page);
-
- if (!same)
- break;
-
- srcoff += cmp_len;
- destoff += cmp_len;
- len -= cmp_len;
- }
-
- *is_same = same;
- return 0;
-
-out_error:
- return error;
-}
-EXPORT_SYMBOL(vfs_dedupe_file_range_compare);
-
loff_t vfs_dedupe_file_range_one(struct file *src_file, loff_t src_pos,
struct file *dst_file, loff_t dst_pos,
loff_t len, unsigned int remap_flags)
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 34c22d695011..346036a84f18 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1853,9 +1853,6 @@ extern loff_t do_clone_file_range(struct file *file_in, loff_t pos_in,
extern loff_t vfs_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);
-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);
extern int vfs_dedupe_file_range(struct file *file,
struct file_dedupe_range *same);
extern loff_t vfs_dedupe_file_range_one(struct file *src_file, loff_t src_pos,