This patch adds an ioctl, BTRFS_IOC_FILE_EXTENT_SAME which will try to
de-duplicate a list of extents across a range of files.
Internally, the ioctl re-uses code from the clone ioctl. This avoids
rewriting a large chunk of extent handling code.
Userspace passes in an array of file, offset pairs along with a length
argument. The ioctl will then (for each dedupe) do a byte-by-byte comparison
of the user data before deduping the extent. Status and number of bytes
deduped are returned for each operation.
Signed-off-by: Mark Fasheh <mfas...@suse.de>
---
fs/btrfs/ioctl.c | 278 +++++++++++++++++++++++++++++++++++++++++++++
include/uapi/linux/btrfs.h | 27 +++++
2 files changed, 305 insertions(+)
diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index e90c519..7db2ee6 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -57,6 +57,9 @@
#include "send.h"
#include "dev-replace.h"
+static int btrfs_clone(struct inode *src, struct inode *inode,
+ u64 off, u64 olen, u64 olen_aligned, u64 destoff);
+
/* Mask out flags that are inappropriate for the given type of inode. */
static inline __u32 btrfs_mask_flags(umode_t mode, __u32 flags)
{
@@ -2456,6 +2459,34 @@ out:
return ret;
}
+static struct page *extent_same_get_page(struct inode *inode, u64 off)
+{
+ struct page *page;
+ pgoff_t index;
+ struct extent_io_tree *tree = &BTRFS_I(inode)->io_tree;
+
+ index = off >> PAGE_CACHE_SHIFT;
+
+ page = grab_cache_page(inode->i_mapping, index);
+ if (!page)
+ return NULL;
+
+ if (!PageUptodate(page)) {
+ if (extent_read_full_page_nolock(tree, page, btrfs_get_extent,
+ 0))
+ return NULL;
+ lock_page(page);
+ if (!PageUptodate(page)) {
+ unlock_page(page);
+ page_cache_release(page);
+ return NULL;
+ }
+ }
+ unlock_page(page);
+
+ return page;
+}
+
static inline void lock_extent_range(struct inode *inode, u64 off, u64 len)
{
/* do any pending delalloc/csum calc on src, one way or
@@ -2476,6 +2507,251 @@ static inline void lock_extent_range(struct inode
*inode, u64 off, u64 len)
}
}
+static void btrfs_double_unlock(struct inode *inode1, u64 loff1,
+ struct inode *inode2, u64 loff2, u64 len)
+{
+ unlock_extent(&BTRFS_I(inode1)->io_tree, loff1, loff1 + len - 1);
+ unlock_extent(&BTRFS_I(inode2)->io_tree, loff2, loff2 + len - 1);
+
+ mutex_unlock(&inode1->i_mutex);
+ mutex_unlock(&inode2->i_mutex);
+}
+
+static void btrfs_double_lock(struct inode *inode1, u64 loff1,
+ struct inode *inode2, u64 loff2, u64 len)
+{
+ if (inode1 < inode2) {
+ swap(inode1, inode2);
+ swap(loff1, loff2);
+ }
+
+ mutex_lock_nested(&inode1->i_mutex, I_MUTEX_PARENT);
+ lock_extent_range(inode1, loff1, len);
+ if (inode1 != inode2) {
+ mutex_lock_nested(&inode2->i_mutex, I_MUTEX_CHILD);
+ lock_extent_range(inode2, loff2, len);
+ }
+}
+
+static int btrfs_cmp_data(struct inode *src, u64 loff, struct inode *dst,
+ u64 dst_loff, u64 len)
+{
+ int ret = 0;
+ struct page *src_page, *dst_page;
+ unsigned int cmp_len = PAGE_CACHE_SIZE;
+ void *addr, *dst_addr;
+
+ while (len) {
+ if (len < PAGE_CACHE_SIZE)
+ cmp_len = len;
+
+ src_page = extent_same_get_page(src, loff);
+ if (!src_page)
+ return -EINVAL;
+ dst_page = extent_same_get_page(dst, dst_loff);
+ if (!dst_page) {
+ page_cache_release(src_page);
+ return -EINVAL;
+ }
+ addr = kmap_atomic(src_page);
+ dst_addr = kmap_atomic(dst_page);
+
+ flush_dcache_page(src_page);
+ flush_dcache_page(dst_page);
+
+ if (memcmp(addr, dst_addr, cmp_len))
+ ret = BTRFS_SAME_DATA_DIFFERS;
+
+ kunmap_atomic(addr);
+ kunmap_atomic(dst_addr);
+ page_cache_release(src_page);
+ page_cache_release(dst_page);
+
+ if (ret)
+ break;
+
+ loff += cmp_len;
+ dst_loff += cmp_len;
+ len -= cmp_len;
+ }
+
+ return ret;
+}
+
+static int extent_same_check_offsets(struct inode *inode, u64 off, u64 len)
+{
+ u64 bs = BTRFS_I(inode)->root->fs_info->sb->s_blocksize;
+
+ if (off + len > inode->i_size || off + len < off)
+ return -EINVAL;
+ /* Check that we are block aligned - btrfs_clone() requires this */
+ if (!IS_ALIGNED(off, bs) || !IS_ALIGNED(off + len, bs))
+ return -EINVAL;
+
+ return 0;
+}
+
+static int btrfs_extent_same(struct inode *src, u64 loff, u64 len,
+ struct inode *dst, u64 dst_loff)
+{
+ int ret;
+
+ /*
+ * btrfs_clone() can't handle extents in the same file
+ * yet. Once that works, we can drop this check and replace it
+ * with a check for the same inode, but overlapping extents.
+ */
+ if (src == dst)
+ return -EINVAL;
+
+ btrfs_double_lock(src, loff, dst, dst_loff, len);
+
+ ret = extent_same_check_offsets(src, loff, len);
+ if (ret)
+ goto out_unlock;
+
+ ret = extent_same_check_offsets(dst, dst_loff, len);
+ if (ret)
+ goto out_unlock;
+
+ /* don't make the dst file partly checksummed */
+ if ((BTRFS_I(src)->flags & BTRFS_INODE_NODATASUM) !=
+ (BTRFS_I(dst)->flags & BTRFS_INODE_NODATASUM)) {
+ ret = -EINVAL;
+ goto out_unlock;
+ }
+
+ ret = btrfs_cmp_data(src, loff, dst, dst_loff, len);
+ if (ret == 0)
+ ret = btrfs_clone(src, dst, loff, len, len, dst_loff);
+
+out_unlock:
+ btrfs_double_unlock(src, loff, dst, dst_loff, len);
+
+ return ret;
+}
+
+#define BTRFS_MAX_DEDUPE_LEN (16 * 1024 * 1024)
+
+static long btrfs_ioctl_file_extent_same(struct file *file,
+ void __user *argp)
+{
+ struct btrfs_ioctl_same_args *args = argp;
+ struct btrfs_ioctl_same_args same;
+ struct btrfs_ioctl_same_extent_info info;
+ struct inode *src = file->f_dentry->d_inode;
+ struct file *dst_file = NULL;
+ struct inode *dst;
+ u64 off;
+ u64 len;
+ int i;
+ int ret;
+ u64 bs = BTRFS_I(src)->root->fs_info->sb->s_blocksize;
+ bool is_admin = capable(CAP_SYS_ADMIN);
+
+ if (!(file->f_mode & FMODE_READ))
+ return -EINVAL;
+
+ ret = mnt_want_write_file(file);
+ if (ret)
+ return ret;
+
+ if (copy_from_user(&same,
+ (struct btrfs_ioctl_same_args __user *)argp,
+ sizeof(same))) {
+ ret = -EFAULT;
+ goto out;
+ }
+
+ off = same.logical_offset;
+ len = same.length;
+
+ /*
+ * Limit the total length we will dedupe for each operation.
+ * This is intended to bound the total time spent in this
+ * ioctl to something sane.
+ */
+ if (len > BTRFS_MAX_DEDUPE_LEN)
+ len = BTRFS_MAX_DEDUPE_LEN;
+
+ if (WARN_ON_ONCE(bs < PAGE_CACHE_SIZE)) {
+ /*
+ * Btrfs does not support blocksize < page_size. As a
+ * result, btrfs_cmp_data() won't correctly handle
+ * this situation without an update.
+ */
+ ret = -EINVAL;
+ goto out;
+ }
+
+ ret = -EISDIR;
+ if (S_ISDIR(src->i_mode))
+ goto out;
+
+ ret = -EACCES;
+ if (!S_ISREG(src->i_mode))
+ goto out;
+
+ ret = 0;
+ for (i = 0; i < same.dest_count; i++) {
+ if (copy_from_user(&info, &args->info[i], sizeof(info))) {
+ ret = -EFAULT;
+ goto out;
+ }
+
+ info.bytes_deduped = 0;
+
+ dst_file = fget(info.fd);
+ if (!dst_file) {
+ info.status = -EBADF;
+ goto next;
+ }
+
+ if (!(is_admin || (dst_file->f_mode & FMODE_WRITE))) {
+ info.status = -EINVAL;
+ goto next;
+ }
+
+ info.status = -EXDEV;
+ if (file->f_path.mnt != dst_file->f_path.mnt)
+ goto next;
+
+ dst = dst_file->f_dentry->d_inode;
+ if (src->i_sb != dst->i_sb)
+ goto next;
+
+ if (S_ISDIR(dst->i_mode)) {
+ info.status = -EISDIR;
+ goto next;
+ }
+
+ if (!S_ISREG(dst->i_mode)) {
+ info.status = -EACCES;
+ goto next;
+ }
+
+ info.status = btrfs_extent_same(src, off, len, dst,
+ info.logical_offset);
+ if (info.status == 0)
+ info.bytes_deduped += len;
+
+next:
+ if (dst_file)
+ fput(dst_file);
+
+ if (__put_user_unaligned(info.status, &args->info[i].status) ||
+ __put_user_unaligned(info.bytes_deduped,
+ &args->info[i].bytes_deduped)) {
+ ret = -EFAULT;
+ goto out;
+ }
+ }
+
+out:
+ mnt_drop_write_file(file);
+ return ret;
+}
+
/**
* btrfs_clone() - clone a range from inode file to another
*
@@ -4151,6 +4427,8 @@ long btrfs_ioctl(struct file *file, unsigned int
return btrfs_ioctl_get_fslabel(file, argp);
case BTRFS_IOC_SET_FSLABEL:
return btrfs_ioctl_set_fslabel(file, argp);
+ case BTRFS_IOC_FILE_EXTENT_SAME:
+ return btrfs_ioctl_file_extent_same(file, argp);
}
return -ENOTTY;
diff --git a/include/uapi/linux/btrfs.h b/include/uapi/linux/btrfs.h
index fa3a5f9..5465bc2 100644
--- a/include/uapi/linux/btrfs.h
+++ b/include/uapi/linux/btrfs.h
@@ -305,6 +305,31 @@ struct btrfs_ioctl_clone_range_args {
#define BTRFS_DEFRAG_RANGE_COMPRESS 1
#define BTRFS_DEFRAG_RANGE_START_IO 2
+#define BTRFS_SAME_DATA_DIFFERS 1
+/* For extent-same ioctl */
+struct btrfs_ioctl_same_extent_info {
+ __s64 fd; /* in - destination file */
+ __u64 logical_offset; /* in - start of extent in destination */
+ __u64 bytes_deduped; /* out - total # of bytes we were able
+ * to dedupe from this file */
+ /* status of this dedupe operation:
+ * 0 if dedup succeeds
+ * < 0 for error
+ * == BTRFS_SAME_DATA_DIFFERS if data differs
+ */
+ __s32 status; /* out - see above description */
+ __u32 reserved;
+};
+
+struct btrfs_ioctl_same_args {
+ __u64 logical_offset; /* in - start of extent in source */
+ __u64 length; /* in - length of extent */
+ __u16 dest_count; /* in - total elements in info array */
+ __u16 reserved1;
+ __u32 reserved2;
+ struct btrfs_ioctl_same_extent_info info[0];
+};
+
struct btrfs_ioctl_space_info {
__u64 flags;
__u64 total_bytes;
@@ -510,5 +535,7 @@ struct btrfs_ioctl_send_args {
struct btrfs_ioctl_get_dev_stats)
#define BTRFS_IOC_DEV_REPLACE _IOWR(BTRFS_IOCTL_MAGIC, 53, \
struct btrfs_ioctl_dev_replace_args)
+#define BTRFS_IOC_FILE_EXTENT_SAME _IOWR(BTRFS_IOCTL_MAGIC, 54, \
+ struct btrfs_ioctl_same_args)
#endif /* _UAPI_LINUX_BTRFS_H */
--
1.8.1.4
--
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