@@ -861,6 +861,134 @@ struct btrfs_ioctl_get_subvol_rootref_args {
__u8 align[7];
};
+/*
+ * Data and metadata for an encoded read or write.
+ *
+ * Encoded I/O bypasses any encoding automatically done by the filesystem (e.g.,
+ * compression). This can be used to read the compressed contents of a file or
+ * write pre-compressed data directly to a file.
+ *
+ * BTRFS_IOC_ENCODED_READ and BTRFS_IOC_ENCODED_WRITE are essentially
+ * preadv/pwritev with additional metadata about how the data is encoded and the
+ * size of the unencoded data.
+ *
+ * BTRFS_IOC_ENCODED_READ fills the given iovecs with the encoded data, fills
+ * the metadata fields, and returns the size of the encoded data. It reads one
+ * extent per call. It can also read data which is not encoded.
+ *
+ * BTRFS_IOC_ENCODED_WRITE uses the metadata fields, writes the encoded data
+ * from the iovecs, and returns the size of the encoded data. Note that the
+ * encoded data is not validated when it is written; if it is not valid (e.g.,
+ * it cannot be decompressed), then a subsequent read may return an error.
+ *
+ * Since the filesystem page cache contains decoded data, encoded I/O bypasses
+ * the page cache. Encoded I/O requires CAP_SYS_ADMIN.
+ */
+struct btrfs_ioctl_encoded_io_args {
+ /* Input parameters for both reads and writes. */
+
+ /*
+ * iovecs containing encoded data.
+ *
+ * For reads, if the size of the encoded data is larger than the sum of
+ * iov[n].iov_len for 0 <= n < iovcnt, then the ioctl fails with
+ * ENOBUFS.
+ *
+ * For writes, the size of the encoded data is the sum of iov[n].iov_len
+ * for 0 <= n < iovcnt. This must be less than 128 KiB (this limit may
+ * increase in the future). This must also be less than or equal to
+ * unencoded_len.
+ */
+ const struct iovec __user *iov;
+ /* Number of iovecs. */
+ unsigned long iovcnt;
+ /*
+ * Offset in file.
+ *
+ * For writes, must be aligned to the sector size of the filesystem.
+ */
+ __s64 offset;
+ /* Currently must be zero. */
+ __u64 flags;
+
+ /*
+ * For reads, the following members are filled in with the metadata for
+ * the encoded data.
+ * For writes, the following members must be set to the metadata for the
+ * encoded data.
+ */
+
+ /*
+ * Length of the data in the file.
+ *
+ * Must be less than or equal to unencoded_len - unencoded_offset. For
+ * writes, must be aligned to the sector size of the filesystem unless
+ * the data ends at or beyond the current end of the file.
+ */
+ __u64 len;
+ /*
+ * Length of the unencoded (i.e., decrypted and decompressed) data.
+ *
+ * For writes, must be no more than 128 KiB (this limit may increase in
+ * the future). If the unencoded data is actually longer than
+ * unencoded_len, then it is truncated; if it is shorter, then it is
+ * extended with zeroes.
+ */
+ __u64 unencoded_len;
+ /*
+ * Offset from the first byte of the unencoded data to the first byte of
+ * logical data in the file.
+ *
+ * Must be less than unencoded_len.
+ */
+ __u64 unencoded_offset;
+ /*
+ * BTRFS_ENCODED_IO_COMPRESSION_* type.
+ *
+ * For writes, must not be BTRFS_ENCODED_IO_COMPRESSION_NONE.
+ */
+ __u32 compression;
+ /* Currently always BTRFS_ENCODED_IO_ENCRYPTION_NONE. */
+ __u32 encryption;
+ /*
+ * Reserved for future expansion.
+ *
+ * For reads, always returned as zero. Users should check for non-zero
+ * bytes. If there are any, then the kernel has a newer version of this
+ * structure with additional information that the user definition is
+ * missing.
+ *
+ * For writes, must be zeroed.
+ */
+ __u8 reserved[32];
+};
+
+/* Data is not compressed. */
+#define BTRFS_ENCODED_IO_COMPRESSION_NONE 0
+/* Data is compressed as a single zlib stream. */
+#define BTRFS_ENCODED_IO_COMPRESSION_ZLIB 1
+/*
+ * Data is compressed as a single zstd frame with the windowLog compression
+ * parameter set to no more than 17.
+ */
+#define BTRFS_ENCODED_IO_COMPRESSION_ZSTD 2
+/*
+ * Data is compressed page by page (using the page size indicated by the name of
+ * the constant) with LZO1X and wrapped in the format documented in
+ * fs/btrfs/lzo.c. For writes, the compression page size must match the
+ * filesystem page size.
+ */
+#define BTRFS_ENCODED_IO_COMPRESSION_LZO_4K 3
+#define BTRFS_ENCODED_IO_COMPRESSION_LZO_8K 4
+#define BTRFS_ENCODED_IO_COMPRESSION_LZO_16K 5
+#define BTRFS_ENCODED_IO_COMPRESSION_LZO_32K 6
+#define BTRFS_ENCODED_IO_COMPRESSION_LZO_64K 7
+#define BTRFS_ENCODED_IO_COMPRESSION_TYPES 8
+
+/* Data is not encrypted. */
+#define BTRFS_ENCODED_IO_ENCRYPTION_NONE 0
+#define BTRFS_ENCODED_IO_ENCRYPTION_TYPES 1
+
/* Error codes as returned by the kernel */
enum btrfs_err_code {
BTRFS_ERROR_DEV_RAID1_MIN_NOT_MET = 1,
@@ -989,5 +1117,9 @@ enum btrfs_err_code {
struct btrfs_ioctl_ino_lookup_user_args)
#define BTRFS_IOC_SNAP_DESTROY_V2 _IOW(BTRFS_IOCTL_MAGIC, 63, \
struct btrfs_ioctl_vol_args_v2)
+#define BTRFS_IOC_ENCODED_READ _IOR(BTRFS_IOCTL_MAGIC, 64, \
+ struct btrfs_ioctl_encoded_io_args)
+#define BTRFS_IOC_ENCODED_WRITE _IOW(BTRFS_IOCTL_MAGIC, 64, \
+ struct btrfs_ioctl_encoded_io_args)
#endif /* _UAPI_LINUX_BTRFS_H */