diff options
| author | Gerhard Heift <gerhard@heift.name> | 2014-01-30 16:24:01 +0100 |
|---|---|---|
| committer | Chris Mason <clm@fb.com> | 2014-06-12 18:21:56 -0700 |
| commit | 550ac1d85ef99f3390a6ea87c70b7683647f6110 (patch) | |
| tree | a3753a08098118a0dda00aff8fcf4dc20e3a480a | |
| parent | 9b6e817d022fd44fe99db92f00d4b18ac2d8f429 (diff) | |
| download | linux-550ac1d85ef99f3390a6ea87c70b7683647f6110.tar.gz | |
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>
| -rw-r--r-- | fs/btrfs/extent_io.c | 37 | ||||
| -rw-r--r-- | fs/btrfs/extent_io.h | 3 |
2 files changed, 40 insertions, 0 deletions
diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c index 0b5fa91d9a8893..930f23dfaa2b47 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 8b63f2d46518e8..15ce5f2a2b624f 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, |