diff mbox series

[v11,06/14] btrfs: optionally extend i_size in cow_file_range_inline()

Message ID 54ad4e1fe7d6c4dce4a87fd4f22de3a7b197d13b.1630514529.git.osandov@fb.com (mailing list archive)
State New, archived
Headers show
Series btrfs: add ioctls and send/receive support for reading/writing compressed data | expand

Commit Message

Omar Sandoval Sept. 1, 2021, 5:01 p.m. UTC 
From: Omar Sandoval <osandov@fb.com>

Currently, an inline extent is always created after i_size is extended
from btrfs_dirty_pages(). However, for encoded writes, we only want to
update i_size after we successfully created the inline extent. Add an
update_i_size parameter to cow_file_range_inline() and
insert_inline_extent() and pass in the size of the extent rather than
determining it from i_size. Since the start parameter is always passed
as 0, get rid of it and simplify the logic in these two functions. While
we're here, let's document the requirements for creating an inline
extent.

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Omar Sandoval <osandov@fb.com>
---
 fs/btrfs/inode.c | 100 +++++++++++++++++++++++------------------------
 1 file changed, 48 insertions(+), 52 deletions(-)

Comments

Nikolay Borisov Oct. 14, 2021, 12:54 p.m. UTC | #1 
On 1.09.21 г. 20:01, Omar Sandoval wrote:
> From: Omar Sandoval <osandov@fb.com>
> 
> Currently, an inline extent is always created after i_size is extended
> from btrfs_dirty_pages(). However, for encoded writes, we only want to
> update i_size after we successfully created the inline extent. Add an
> update_i_size parameter to cow_file_range_inline() and
> insert_inline_extent() and pass in the size of the extent rather than
> determining it from i_size. Since the start parameter is always passed
> as 0, get rid of it and simplify the logic in these two functions. While
> we're here, let's document the requirements for creating an inline
> extent.
> 
> Reviewed-by: Josef Bacik <josef@toxicpanda.com>
> Signed-off-by: Omar Sandoval <osandov@fb.com>


Overall I like where this is going, actually the diff is larger than it
should be because some refactoring is tucked in. If there would be yet
another submission with more substantial changes I'd like to see this
patch split into 2:

1. Patch does the refactoring

2. Adds the logic to update i_size alongside the addition of the
update_i_size parameter.

That will make the functional change a lot more obvious.

> ---
>  fs/btrfs/inode.c | 100 +++++++++++++++++++++++------------------------
>  1 file changed, 48 insertions(+), 52 deletions(-)
> 
> diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
> index 6aad4b641d5c..a87a34f56234 100644
> --- a/fs/btrfs/inode.c
> +++ b/fs/btrfs/inode.c
> @@ -236,9 +236,10 @@ static int btrfs_init_inode_security(struct btrfs_trans_handle *trans,
>  static int insert_inline_extent(struct btrfs_trans_handle *trans,
>  				struct btrfs_path *path, bool extent_inserted,
>  				struct btrfs_root *root, struct inode *inode,
> -				u64 start, size_t size, size_t compressed_size,
> +				size_t size, size_t compressed_size,
>  				int compress_type,
> -				struct page **compressed_pages)
> +				struct page **compressed_pages,
> +				bool update_i_size)

This function grows to 10 parameters, I think it's high time it took an
argument struct and each member can in turn be documented in this
structure,  otherwise it's very unwieldy to work with.

>  {
>  	struct extent_buffer *leaf;
>  	struct page *page = NULL;

<snip>


>  
> @@ -327,7 +326,13 @@ static int insert_inline_extent(struct btrfs_trans_handle *trans,
>  	 * before we unlock the pages.  Otherwise we
>  	 * could end up racing with unlink.
>  	 */
> -	BTRFS_I(inode)->disk_i_size = inode->i_size;
> +	i_size = i_size_read(inode);
> +	if (update_i_size && size > i_size) {
> +		i_size_write(inode, size);
> +		i_size = size;
> +	}
> +	BTRFS_I(inode)->disk_i_size = i_size;
> +
>  fail:
>  	return ret;
>  }
> @@ -338,35 +343,31 @@ static int insert_inline_extent(struct btrfs_trans_handle *trans,
>   * does the checks required to make sure the data is small enough
>   * to fit as an inline extent.
>   */
> -static noinline int cow_file_range_inline(struct btrfs_inode *inode, u64 start,
> -					  u64 end, size_t compressed_size,
> +static noinline int cow_file_range_inline(struct btrfs_inode *inode, u64 size,
> +					  size_t compressed_size,
>  					  int compress_type,
> -					  struct page **compressed_pages)
> +					  struct page **compressed_pages,
> +					  bool update_i_size)

This function also has 6 parameters which is not on the extreme but I
have a feeling it also needs to be refactored to take an argument
structure.

>  {
>  	struct btrfs_drop_extents_args drop_args = { 0 };
>  	struct btrfs_root *root = inode->root;
>  	struct btrfs_fs_info *fs_info = root->fs_info;
>  	struct btrfs_trans_handle *trans;
> -	u64 isize = i_size_read(&inode->vfs_inode);
> -	u64 actual_end = min(end + 1, isize);
> -	u64 inline_len = actual_end - start;
> -	u64 aligned_end = ALIGN(end, fs_info->sectorsize);
> -	u64 data_len = inline_len;
> +	u64 data_len = compressed_size ? compressed_size : size;
>  	int ret;
>  	struct btrfs_path *path;
>  
> -	if (compressed_size)
> -		data_len = compressed_size;
> -
> -	if (start > 0 ||
> -	    actual_end > fs_info->sectorsize ||
> +	/*
> +	 * We can create an inline extent if it ends at or beyond the current
> +	 * i_size, is no larger than a sector (decompressed), and the (possibly
> +	 * compressed) data fits in a leaf and the configured maximum inline
> +	 * size.
> +	 */
> +	if (size < i_size_read(&inode->vfs_inode) ||
> +	    size > fs_info->sectorsize ||
>  	    data_len > BTRFS_MAX_INLINE_DATA_SIZE(fs_info) ||
> -	    (!compressed_size &&
> -	    (actual_end & (fs_info->sectorsize - 1)) == 0) ||
> -	    end + 1 < isize ||
> -	    data_len > fs_info->max_inline) {
> +	    data_len > fs_info->max_inline)
>  		return 1;

With this change you allow to write more than PAGE_SIZE data in case of
a compressed extents, Qu said he had some concerns regarding this. I'm
CCing him so this can be discussed on this submission.

> -	}
>  
>  	path = btrfs_alloc_path();
>  	if (!path)

<snip>
diff mbox series

Patch

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 6aad4b641d5c..a87a34f56234 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -236,9 +236,10 @@  static int btrfs_init_inode_security(struct btrfs_trans_handle *trans,
 static int insert_inline_extent(struct btrfs_trans_handle *trans,
 				struct btrfs_path *path, bool extent_inserted,
 				struct btrfs_root *root, struct inode *inode,
-				u64 start, size_t size, size_t compressed_size,
+				size_t size, size_t compressed_size,
 				int compress_type,
-				struct page **compressed_pages)
+				struct page **compressed_pages,
+				bool update_i_size)
 {
 	struct extent_buffer *leaf;
 	struct page *page = NULL;
@@ -247,7 +248,7 @@  static int insert_inline_extent(struct btrfs_trans_handle *trans,
 	struct btrfs_file_extent_item *ei;
 	int ret;
 	size_t cur_size = size;
-	unsigned long offset;
+	u64 i_size;
 
 	ASSERT((compressed_size > 0 && compressed_pages) ||
 	       (compressed_size == 0 && !compressed_pages));
@@ -260,7 +261,7 @@  static int insert_inline_extent(struct btrfs_trans_handle *trans,
 		size_t datasize;
 
 		key.objectid = btrfs_ino(BTRFS_I(inode));
-		key.offset = start;
+		key.offset = 0;
 		key.type = BTRFS_EXTENT_DATA_KEY;
 
 		datasize = btrfs_file_extent_calc_inline_size(cur_size);
@@ -297,12 +298,10 @@  static int insert_inline_extent(struct btrfs_trans_handle *trans,
 		btrfs_set_file_extent_compression(leaf, ei,
 						  compress_type);
 	} else {
-		page = find_get_page(inode->i_mapping,
-				     start >> PAGE_SHIFT);
+		page = find_get_page(inode->i_mapping, 0);
 		btrfs_set_file_extent_compression(leaf, ei, 0);
 		kaddr = kmap_atomic(page);
-		offset = offset_in_page(start);
-		write_extent_buffer(leaf, kaddr + offset, ptr, size);
+		write_extent_buffer(leaf, kaddr, ptr, size);
 		kunmap_atomic(kaddr);
 		put_page(page);
 	}
@@ -313,8 +312,8 @@  static int insert_inline_extent(struct btrfs_trans_handle *trans,
 	 * We align size to sectorsize for inline extents just for simplicity
 	 * sake.
 	 */
-	size = ALIGN(size, root->fs_info->sectorsize);
-	ret = btrfs_inode_set_file_extent_range(BTRFS_I(inode), start, size);
+	ret = btrfs_inode_set_file_extent_range(BTRFS_I(inode), 0,
+					ALIGN(size, root->fs_info->sectorsize));
 	if (ret)
 		goto fail;
 
@@ -327,7 +326,13 @@  static int insert_inline_extent(struct btrfs_trans_handle *trans,
 	 * before we unlock the pages.  Otherwise we
 	 * could end up racing with unlink.
 	 */
-	BTRFS_I(inode)->disk_i_size = inode->i_size;
+	i_size = i_size_read(inode);
+	if (update_i_size && size > i_size) {
+		i_size_write(inode, size);
+		i_size = size;
+	}
+	BTRFS_I(inode)->disk_i_size = i_size;
+
 fail:
 	return ret;
 }
@@ -338,35 +343,31 @@  static int insert_inline_extent(struct btrfs_trans_handle *trans,
  * does the checks required to make sure the data is small enough
  * to fit as an inline extent.
  */
-static noinline int cow_file_range_inline(struct btrfs_inode *inode, u64 start,
-					  u64 end, size_t compressed_size,
+static noinline int cow_file_range_inline(struct btrfs_inode *inode, u64 size,
+					  size_t compressed_size,
 					  int compress_type,
-					  struct page **compressed_pages)
+					  struct page **compressed_pages,
+					  bool update_i_size)
 {
 	struct btrfs_drop_extents_args drop_args = { 0 };
 	struct btrfs_root *root = inode->root;
 	struct btrfs_fs_info *fs_info = root->fs_info;
 	struct btrfs_trans_handle *trans;
-	u64 isize = i_size_read(&inode->vfs_inode);
-	u64 actual_end = min(end + 1, isize);
-	u64 inline_len = actual_end - start;
-	u64 aligned_end = ALIGN(end, fs_info->sectorsize);
-	u64 data_len = inline_len;
+	u64 data_len = compressed_size ? compressed_size : size;
 	int ret;
 	struct btrfs_path *path;
 
-	if (compressed_size)
-		data_len = compressed_size;
-
-	if (start > 0 ||
-	    actual_end > fs_info->sectorsize ||
+	/*
+	 * We can create an inline extent if it ends at or beyond the current
+	 * i_size, is no larger than a sector (decompressed), and the (possibly
+	 * compressed) data fits in a leaf and the configured maximum inline
+	 * size.
+	 */
+	if (size < i_size_read(&inode->vfs_inode) ||
+	    size > fs_info->sectorsize ||
 	    data_len > BTRFS_MAX_INLINE_DATA_SIZE(fs_info) ||
-	    (!compressed_size &&
-	    (actual_end & (fs_info->sectorsize - 1)) == 0) ||
-	    end + 1 < isize ||
-	    data_len > fs_info->max_inline) {
+	    data_len > fs_info->max_inline)
 		return 1;
-	}
 
 	path = btrfs_alloc_path();
 	if (!path)
@@ -380,30 +381,21 @@  static noinline int cow_file_range_inline(struct btrfs_inode *inode, u64 start,
 	trans->block_rsv = &inode->block_rsv;
 
 	drop_args.path = path;
-	drop_args.start = start;
-	drop_args.end = aligned_end;
+	drop_args.start = 0;
+	drop_args.end = fs_info->sectorsize;
 	drop_args.drop_cache = true;
 	drop_args.replace_extent = true;
-
-	if (compressed_size && compressed_pages)
-		drop_args.extent_item_size = btrfs_file_extent_calc_inline_size(
-		   compressed_size);
-	else
-		drop_args.extent_item_size = btrfs_file_extent_calc_inline_size(
-		    inline_len);
-
+	drop_args.extent_item_size = btrfs_file_extent_calc_inline_size(data_len);
 	ret = btrfs_drop_extents(trans, root, inode, &drop_args);
 	if (ret) {
 		btrfs_abort_transaction(trans, ret);
 		goto out;
 	}
 
-	if (isize > actual_end)
-		inline_len = min_t(u64, isize, actual_end);
-	ret = insert_inline_extent(trans, path, drop_args.extent_inserted,
-				   root, &inode->vfs_inode, start,
-				   inline_len, compressed_size,
-				   compress_type, compressed_pages);
+	ret = insert_inline_extent(trans, path, drop_args.extent_inserted, root,
+				   &inode->vfs_inode, size, compressed_size,
+				   compress_type, compressed_pages,
+				   update_i_size);
 	if (ret && ret != -ENOSPC) {
 		btrfs_abort_transaction(trans, ret);
 		goto out;
@@ -412,7 +404,7 @@  static noinline int cow_file_range_inline(struct btrfs_inode *inode, u64 start,
 		goto out;
 	}
 
-	btrfs_update_inode_bytes(inode, inline_len, drop_args.bytes_found);
+	btrfs_update_inode_bytes(inode, size, drop_args.bytes_found);
 	ret = btrfs_update_inode(trans, root, inode);
 	if (ret && ret != -ENOSPC) {
 		btrfs_abort_transaction(trans, ret);
@@ -695,14 +687,15 @@  static noinline int compress_file_range(struct async_chunk *async_chunk)
 			/* we didn't compress the entire range, try
 			 * to make an uncompressed inline extent.
 			 */
-			ret = cow_file_range_inline(BTRFS_I(inode), start, end,
+			ret = cow_file_range_inline(BTRFS_I(inode), actual_end,
 						    0, BTRFS_COMPRESS_NONE,
-						    NULL);
+						    NULL, false);
 		} else {
 			/* try making a compressed inline extent */
-			ret = cow_file_range_inline(BTRFS_I(inode), start, end,
+			ret = cow_file_range_inline(BTRFS_I(inode), actual_end,
 						    total_compressed,
-						    compress_type, pages);
+						    compress_type, pages,
+						    false);
 		}
 		if (ret <= 0) {
 			unsigned long clear_flags = EXTENT_DELALLOC |
@@ -1098,9 +1091,12 @@  static noinline int cow_file_range(struct btrfs_inode *inode,
 	 * So here we skip inline extent creation completely.
 	 */
 	if (start == 0 && fs_info->sectorsize == PAGE_SIZE) {
+		u64 actual_end = min_t(u64, i_size_read(&inode->vfs_inode),
+				       end + 1);
+
 		/* lets try to make an inline extent */
-		ret = cow_file_range_inline(inode, start, end, 0,
-					    BTRFS_COMPRESS_NONE, NULL);
+		ret = cow_file_range_inline(inode, actual_end, 0,
+					    BTRFS_COMPRESS_NONE, NULL, false);
 		if (ret == 0) {
 			/*
 			 * We use DO_ACCOUNTING here because we need the