Re: [PATCH v11 09/10] btrfs-progs: send: stream v2 ioctl flags
From: Nikolay Borisov <hidden>
Date: 2021-10-22 06:35:41
Also in:
linux-btrfs, linux-fsdevel
On 1.09.21 г. 20:01, Omar Sandoval wrote:
From: Boris Burkov <redacted> To make the btrfs send ioctl use the stream v2 format requires passing BTRFS_SEND_FLAG_STREAM_V2 in flags. Further, to cause the ioctl to emit encoded_write commands for encoded extents, we must set that flag as well as BTRFS_SEND_FLAG_COMPRESSED. Finally, we bump up the version in send.h as well, since we are now fully compatible with v2. Add two command line arguments to btrfs send: --stream-version and --compressed-data. --stream-version requires an argument which it parses as an integer and sets STREAM_V2 if the argument is 2. --compressed-data does not require an argument and automatically implies STREAM_V2 as well (COMPRESSED alone causes the ioctl to error out). Some examples to illustrate edge cases: // v1, old format and no encoded_writes btrfs send subvol btrfs send --stream-version 1 subvol // v2 and compressed, we will see encoded_writes btrfs send --compressed-data subvol btrfs send --compressed-data --stream-version 2 subvol // v2 only, new format but no encoded_writes btrfs send --stream-version 2 subvol // error: compressed needs version >= 2 btrfs send --compressed-data --stream-version 1 subvol // error: invalid version (not 1 or 2) btrfs send --stream-version 3 subvol btrfs send --compressed-data --stream-version 0 subvol btrfs send --compressed-data --stream-version 10 subvol
Why would we want to predicate the compressed writes usage on anything other than the stream version?
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Signed-off-by: Boris Burkov <redacted> --- Documentation/btrfs-send.asciidoc | 16 ++++++++- cmds/send.c | 54 ++++++++++++++++++++++++++++++- ioctl.h | 17 +++++++++- libbtrfsutil/btrfs.h | 17 +++++++++- send.h | 2 +- 5 files changed, 101 insertions(+), 5 deletions(-)diff --git a/Documentation/btrfs-send.asciidoc b/Documentation/btrfs-send.asciidoc index c4a05672..202bcd97 100644 --- a/Documentation/btrfs-send.asciidoc +++ b/Documentation/btrfs-send.asciidoc@@ -55,7 +55,21 @@ send in 'NO_FILE_DATA' mode The output stream does not contain any file data and thus cannot be used to transfer changes. This mode is faster and is useful to show the differences in metadata. --q|--quiet:::: + +--stream-version <1|2>:: +Use the given send stream version. The default is 1. Version 2 encodes file +data slightly more efficiently; it is also required for sending compressed data +directly (see '--compressed-data'). Version 2 requires at least btrfs-progs +5.12 on both the sender and receiver and at least Linux 5.12 on the sender. +
The version of progs needs to be adjusted but I assume this will be done by David when this patchset is merged as we don't have a target ATM.
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+--compressed-data:: +Send data that is compressed on the filesystem directly without decompressing +it. If the receiver supports encoded I/O (see `encoded_io`(7)), it can also +write it directly without decompressing it. Otherwise, the receiver will fall +back to decompressing it and writing it normally. This implies +'--stream-version 2'. + +-q|--quiet:: (deprecated) alias for global '-q' option -v|--verbose:: (deprecated) alias for global '-v' optiondiff --git a/cmds/send.c b/cmds/send.c index 3bfc69f5..80eb2510 100644 --- a/cmds/send.c +++ b/cmds/send.c@@ -452,6 +452,21 @@ static const char * const cmd_send_usage[] = { " does not contain any file data and thus cannot be used", " to transfer changes. This mode is faster and useful to", " show the differences in metadata.", + "--stream-version <1|2>", + " Use the given send stream version. The default is", + " 1. Version 2 encodes file data slightly more", + " efficiently; it is also required for sending", + " compressed data directly (see --compressed-data).", + " Version 2 requires at least btrfs-progs 5.12 on both", + " the sender and receiver and at least Linux 5.12 on the", + " sender.",
Ditto <snip>