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authorGerhard Heift <gerhard@heift.name>2014-01-30 16:24:01 +0100
committerChris Mason <clm@fb.com>2014-06-12 18:21:56 -0700
commit550ac1d85ef99f3390a6ea87c70b7683647f6110 (patch)
treea3753a08098118a0dda00aff8fcf4dc20e3a480a /fs/btrfs
parent9b6e817d022fd44fe99db92f00d4b18ac2d8f429 (diff)
btrfs: new function read_extent_buffer_to_user
This new function reads the content of an extent directly to user memory. Signed-off-by: Gerhard Heift <Gerhard@Heift.Name> Signed-off-by: Chris Mason <clm@fb.com> Acked-by: David Sterba <dsterba@suse.cz>
Diffstat (limited to 'fs/btrfs')
-rw-r--r--fs/btrfs/extent_io.c37
-rw-r--r--fs/btrfs/extent_io.h3
2 files changed, 40 insertions, 0 deletions
diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index 0b5fa91d9a88..930f23dfaa2b 100644
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -5067,6 +5067,43 @@ void read_extent_buffer(struct extent_buffer *eb, void *dstv,
}
}
+int read_extent_buffer_to_user(struct extent_buffer *eb, void __user *dstv,
+ unsigned long start,
+ unsigned long len)
+{
+ size_t cur;
+ size_t offset;
+ struct page *page;
+ char *kaddr;
+ char __user *dst = (char __user *)dstv;
+ size_t start_offset = eb->start & ((u64)PAGE_CACHE_SIZE - 1);
+ unsigned long i = (start_offset + start) >> PAGE_CACHE_SHIFT;
+ int ret = 0;
+
+ WARN_ON(start > eb->len);
+ WARN_ON(start + len > eb->start + eb->len);
+
+ offset = (start_offset + start) & (PAGE_CACHE_SIZE - 1);
+
+ while (len > 0) {
+ page = extent_buffer_page(eb, i);
+
+ cur = min(len, (PAGE_CACHE_SIZE - offset));
+ kaddr = page_address(page);
+ if (copy_to_user(dst, kaddr + offset, cur)) {
+ ret = -EFAULT;
+ break;
+ }
+
+ dst += cur;
+ len -= cur;
+ offset = 0;
+ i++;
+ }
+
+ return ret;
+}
+
int map_private_extent_buffer(struct extent_buffer *eb, unsigned long start,
unsigned long min_len, char **map,
unsigned long *map_start,
diff --git a/fs/btrfs/extent_io.h b/fs/btrfs/extent_io.h
index 8b63f2d46518..15ce5f2a2b62 100644
--- a/fs/btrfs/extent_io.h
+++ b/fs/btrfs/extent_io.h
@@ -304,6 +304,9 @@ int memcmp_extent_buffer(struct extent_buffer *eb, const void *ptrv,
void read_extent_buffer(struct extent_buffer *eb, void *dst,
unsigned long start,
unsigned long len);
+int read_extent_buffer_to_user(struct extent_buffer *eb, void __user *dst,
+ unsigned long start,
+ unsigned long len);
void write_extent_buffer(struct extent_buffer *eb, const void *src,
unsigned long start, unsigned long len);
void copy_extent_buffer(struct extent_buffer *dst, struct extent_buffer *src,