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btrfs: add "no file data" flag to btrfs send ioctl

PATCH RESEND In review Mark Fasheh 2 participants 3 messages Jan 30, 2013 – Feb 4, 2013 Btrfs file system

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Mark Fasheh

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#0 lore raw

PATCH RESEND 1/1 btrfs: add "no file data" flag to btrfs send ioctl

This patch adds the flag, BTRFS_SEND_FLAG_NO_FILE_DATA to the btrfs send ioctl code. When this flag is set, the btrfs send code will never write file data into the stream (thus also avoiding expensive reads of that data in the first place). BTRFS_SEND_C_UPDATE_EXTENT commands will be sent (instead of BTRFS_SEND_C_WRITE) with an offset, length pair indicating the extent in question.

This patch does not affect the operation of BTRFS_SEND_C_CLONE commands - they will continue to be sent when a search finds an appropriate extent to clone from.

Signed-off-by Mark Fasheh <[email protected]>
---
 fs/btrfs/ioctl.h |    7 +++++++
 fs/btrfs/send.c  |   48 ++++++++++++++++++++++++++++++++++++++++++++----
 fs/btrfs/send.h  |    1 +
 3 files changed, 52 insertions(+), 4 deletions(-)
fs/btrfs/ioctl.h +7 -0
index 731e287..1f6cfdd 100644
@@ -363,6 +363,13 @@ struct btrfs_ioctl_received_subvol_args {
 	__u64	reserved[16];		/* in */
 };
 
+/*
+ * Caller doesn't want file data in the send stream, even if the
+ * search of clone sources doesn't find an extent. UPDATE_EXTENT
+ * commands will be sent instead of WRITE commands.
+ */
+#define BTRFS_SEND_FLAG_NO_FILE_DATA     0x1
+
 struct btrfs_ioctl_send_args {
 	__s64 send_fd;			/* in */
 	__u64 clone_sources_count;	/* in */
fs/btrfs/send.c +44 -4

79 lines not on this page · raw message

fs/btrfs/send.h +1 -0
index 1bf4f32..8bb18f7 100644
@@ -86,6 +86,7 @@ enum btrfs_send_cmd {
 	BTRFS_SEND_C_UTIMES,
 
 	BTRFS_SEND_C_END,
+	BTRFS_SEND_C_UPDATE_EXTENT,
 	__BTRFS_SEND_C_MAX,
 };
 #define BTRFS_SEND_C_MAX (__BTRFS_SEND_C_MAX - 1)
Signature · 1 line
1.7.10.4
#1 lore raw

fs/btrfs/send.c long btrfs_ioctl_send(struct file *mnt_file, void __user *arg_) · line 4609

Quoted 6 lines · Mark Fasheh
fs/btrfs/send.c +2 -0
@@ -4570,6 +4605,11 @@ long btrfs_ioctl_send(struct file *mnt_file, void __user *arg_)
 	INIT_RADIX_TREE(&sctx->name_cache, GFP_NOFS);
 	INIT_LIST_HEAD(&sctx->name_cache_list);
 
+	if (arg->flags & ~BTRFS_SEND_FLAG_NO_FILE_DATA)
+		return -EINVAL;

Doing just return skips the cleanup block (goto out;), also the test can be placed just after the access_ok() call and skip allocation and init of sctx.

Quoted 6 lines
fs/btrfs/send.c +3 -0
+
+	sctx->flags = arg->flags;
+
 	sctx->send_filp = fget(arg->send_fd);
 	if (IS_ERR(sctx->send_filp)) {
 		ret = PTR_ERR(sctx->send_filp);
author
#2 lore raw
Quoted 11 lines · David Sterba

Review long btrfs_ioctl_send(struct file *mnt_file, void __user *arg_) · line 4609

Quoted 6 lines · Mark Fasheh
(quoted diff) +2 -0
@@ -4570,6 +4605,11 @@ long btrfs_ioctl_send(struct file *mnt_file, void __user *arg_)
 	INIT_RADIX_TREE(&sctx->name_cache, GFP_NOFS);
 	INIT_LIST_HEAD(&sctx->name_cache_list);
 
+	if (arg->flags & ~BTRFS_SEND_FLAG_NO_FILE_DATA)
+		return -EINVAL;

Doing just return skips the cleanup block (goto out;), also the test can be placed just after the access_ok() call and skip allocation and init of sctx.

Ahh, good catch. Sad I missed that one :( A corrected patch is below.

	--Mark

--
Mark Fasheh

From: Mark Fasheh <[email protected]>

[PATCH] btrfs: add "no file data" flag to btrfs send ioctl

This patch adds the flag, BTRFS_SEND_FLAG_NO_FILE_DATA to the btrfs send ioctl code. When this flag is set, the btrfs send code will never write file data into the stream (thus also avoiding expensive reads of that data in the first place). BTRFS_SEND_C_UPDATE_EXTENT commands will be sent (instead of BTRFS_SEND_C_WRITE) with an offset, length pair indicating the extent in question.

This patch does not affect the operation of BTRFS_SEND_C_CLONE commands - they will continue to be sent when a search finds an appropriate extent to clone from.

Signed-off-by Mark Fasheh <[email protected]>
---
 fs/btrfs/ioctl.h |    7 +++++++
 fs/btrfs/send.c  |   50 ++++++++++++++++++++++++++++++++++++++++++++++----
 fs/btrfs/send.h  |    1 +
 3 files changed, 54 insertions(+), 4 deletions(-)
fs/btrfs/ioctl.h +7 -0
index 731e287..1f6cfdd 100644
@@ -363,6 +363,13 @@ struct btrfs_ioctl_received_subvol_args {
 	__u64	reserved[16];		/* in */
 };
 
+/*
+ * Caller doesn't want file data in the send stream, even if the
+ * search of clone sources doesn't find an extent. UPDATE_EXTENT
+ * commands will be sent instead of WRITE commands.
+ */
+#define BTRFS_SEND_FLAG_NO_FILE_DATA     0x1
+
 struct btrfs_ioctl_send_args {
 	__s64 send_fd;			/* in */
 	__u64 clone_sources_count;	/* in */
fs/btrfs/send.c +46 -4

87 lines not on this page · raw message

fs/btrfs/send.h +1 -0
index 1bf4f32..8bb18f7 100644
@@ -86,6 +86,7 @@ enum btrfs_send_cmd {
 	BTRFS_SEND_C_UTIMES,
 
 	BTRFS_SEND_C_END,
+	BTRFS_SEND_C_UPDATE_EXTENT,
 	__BTRFS_SEND_C_MAX,
 };
 #define BTRFS_SEND_C_MAX (__BTRFS_SEND_C_MAX - 1)
Signature · 1 line
1.7.10.4