[PATCH v2 3/4] btrfs: add per-inode compression levels in xattrs

[koraynilay <koray.fra@gmail.com>]

Add support for specifying algo:level using
btrfs property set /path/to/file compression "algo:level".

Add a signed 8 bit prop_compress_level property to btrfs_inode, which
can support from level -128 to 127, plenty for the currently supported
algo:level(s).

Change prop_compression_apply() to use the already present
btrfs_match_compress_type() and btrfs_compress_str2level() to parse the
xattr, using kmemdup_nul() to convert the user-supplied xattr value to a
NUL-terminated string to be used by btrfs_compress_str2level(). The
same approach was taken in prop_compression_validate() for
btrfs_compress_is_valid_type().

Assisted-by: Gemini:3.1-pro antigravity-cli-1.1.5
Signed-off-by: koraynilay <koray.fra@gmail.com>
---
 fs/btrfs/btrfs_inode.h |  1 +
 fs/btrfs/inode.c       |  2 ++
 fs/btrfs/props.c       | 43 +++++++++++++++++++++++++++++++++---------
 3 files changed, 37 insertions(+), 9 deletions(-)

diff --git a/fs/btrfs/btrfs_inode.h b/fs/btrfs/btrfs_inode.h
index 1082fa92c145..0a4e567d0109 100644
--- a/fs/btrfs/btrfs_inode.h
+++ b/fs/btrfs/btrfs_inode.h
@@ -130,6 +130,7 @@ struct btrfs_inode {
 
 	/* Cached value of inode property 'compression'. */
 	u8 prop_compress;
+	s8 prop_compress_level;
 
 	/*
 	 * Force compression on the file using the defrag ioctl, could be
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 2534cd9284d5..cff4b3e97559 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -938,6 +938,7 @@ static void compress_file_range(struct btrfs_work *work)
 		compress_level = inode->defrag_compress_level;
 	} else if (inode->prop_compress) {
 		compress_type = inode->prop_compress;
+		compress_level = inode->prop_compress_level;
 	}
 
 	/* Compression level is applied here. */
@@ -2326,6 +2327,7 @@ static int run_delalloc_inline(struct btrfs_inode *inode, struct folio *locked_f
 			compress_level = inode->defrag_compress_level;
 		} else if (inode->prop_compress) {
 			compress_type = inode->prop_compress;
+			compress_level = inode->prop_compress_level;
 		}
 		cb = btrfs_compress_bio(inode, 0, blocksize, compress_type, compress_level, 0);
 		if (IS_ERR(cb)) {
diff --git a/fs/btrfs/props.c b/fs/btrfs/props.c
index bb77d46376d4..f79a61a2759f 100644
--- a/fs/btrfs/props.c
+++ b/fs/btrfs/props.c
@@ -295,20 +295,28 @@ int btrfs_load_inode_props(struct btrfs_inode *inode, struct btrfs_path *path)
 static int prop_compression_validate(const struct btrfs_inode *inode,
 				     const char *value, size_t len)
 {
+	int ret = -EINVAL;
+	const char *value_str;
+
 	if (!btrfs_inode_can_compress(inode))
 		return -EINVAL;
 
 	if (!value)
 		return 0;
 
-	if (btrfs_compress_is_valid_type(value, len))
-		return 0;
-
 	if ((len == 2 && strncmp("no", value, 2) == 0) ||
 	    (len == 4 && strncmp("none", value, 4) == 0))
 		return 0;
 
-	return -EINVAL;
+	value_str = kmemdup_nul(value, len, GFP_KERNEL);
+	if (!value_str)
+		return -ENOMEM;
+
+	if (btrfs_compress_is_valid_type(value_str))
+		ret = 0;
+
+	kfree(value_str);
+	return ret;
 }
 
 static int prop_compression_apply(struct btrfs_inode *inode, const char *value,
@@ -316,6 +324,9 @@ static int prop_compression_apply(struct btrfs_inode *inode, const char *value,
 {
 	struct btrfs_fs_info *fs_info = inode->root->fs_info;
 	int type;
+	int level = 0;
+	int ret = 0;
+	const char *value_str;
 
 	/* Reset to defaults */
 	if (len == 0) {
@@ -335,23 +346,37 @@ static int prop_compression_apply(struct btrfs_inode *inode, const char *value,
 		return 0;
 	}
 
-	if (!strncmp("lzo", value, 3)) {
+	value_str = kmemdup_nul(value, len, GFP_KERNEL);
+	if (!value_str)
+		return -ENOMEM;
+
+	if (btrfs_match_compress_type(value_str, "lzo", true)) {
 		type = BTRFS_COMPRESS_LZO;
 		btrfs_set_fs_incompat(fs_info, COMPRESS_LZO);
-	} else if (!strncmp("zlib", value, 4)) {
+	} else if (btrfs_match_compress_type(value_str, "zlib", true)) {
 		type = BTRFS_COMPRESS_ZLIB;
-	} else if (!strncmp("zstd", value, 4)) {
+		ret = btrfs_compress_str2level(type, value_str + 4, &level);
+		if (ret < 0)
+			goto out;
+	} else if (btrfs_match_compress_type(value_str, "zstd", true)) {
 		type = BTRFS_COMPRESS_ZSTD;
+		ret = btrfs_compress_str2level(type, value_str + 4, &level);
+		if (ret < 0)
+			goto out;
 		btrfs_set_fs_incompat(fs_info, COMPRESS_ZSTD);
 	} else {
-		return -EINVAL;
+		ret = -EINVAL;
+		goto out;
 	}
 
 	inode->flags &= ~BTRFS_INODE_NOCOMPRESS;
 	inode->flags |= BTRFS_INODE_COMPRESS;
 	inode->prop_compress = type;
+	inode->prop_compress_level = level;
 
-	return 0;
+out:
+	kfree(value_str);
+	return ret;
 }
 
 static bool prop_compression_ignore(const struct btrfs_inode *inode)
-- 
2.55.0