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Message-ID: <20240528164829.2105447-4-willy@infradead.org>
Date: Tue, 28 May 2024 17:48:24 +0100
From: "Matthew Wilcox (Oracle)" <willy@...radead.org>
To: Christoph Hellwig <hch@....de>
Cc: "Matthew Wilcox (Oracle)" <willy@...radead.org>,
linux-fsdevel@...r.kernel.org,
linux-ext4@...r.kernel.org
Subject: [PATCH 3/7] buffer: Add buffer_write_begin, buffer_write_end and __buffer_write_end
These functions are to be called from filesystem implementations of
write_begin and write_end. They correspond to block_write_begin,
generic_write_end and block_write_end. The old functions need to
be kept around as they're used as function pointers.
Signed-off-by: Matthew Wilcox (Oracle) <willy@...radead.org>
---
fs/buffer.c | 80 ++++++++++++++++++++++++++-----------
include/linux/buffer_head.h | 6 +++
2 files changed, 63 insertions(+), 23 deletions(-)
diff --git a/fs/buffer.c b/fs/buffer.c
index 58ac52f20bf6..4064b21fe499 100644
--- a/fs/buffer.c
+++ b/fs/buffer.c
@@ -2217,39 +2217,55 @@ static void __block_commit_write(struct folio *folio, size_t from, size_t to)
}
/*
- * block_write_begin takes care of the basic task of block allocation and
+ * buffer_write_begin - Helper for filesystem write_begin implementations
+ * @mapping: Address space being written to.
+ * @pos: Position in bytes within the file.
+ * @len: Number of bytes being written.
+ * @get_block: How to get buffer_heads for this filesystem.
+ *
+ * Take care of the basic task of block allocation and
* bringing partial write blocks uptodate first.
*
* The filesystem needs to handle block truncation upon failure.
+ *
+ * Return: The folio to write to, or an ERR_PTR on failure.
*/
-int block_write_begin(struct address_space *mapping, loff_t pos, unsigned len,
- struct page **pagep, get_block_t *get_block)
+struct folio *buffer_write_begin(struct address_space *mapping, loff_t pos,
+ size_t len, get_block_t *get_block)
{
- pgoff_t index = pos >> PAGE_SHIFT;
- struct page *page;
+ struct folio *folio = __filemap_get_folio(mapping, pos / PAGE_SIZE,
+ FGP_WRITEBEGIN, mapping_gfp_mask(mapping));
int status;
- page = grab_cache_page_write_begin(mapping, index);
- if (!page)
- return -ENOMEM;
+ if (IS_ERR(folio))
+ return folio;
- status = __block_write_begin(page, pos, len, get_block);
+ status = __block_write_begin_int(folio, pos, len, get_block, NULL);
if (unlikely(status)) {
- unlock_page(page);
- put_page(page);
- page = NULL;
+ folio_unlock(folio);
+ folio_put(folio);
+ folio = ERR_PTR(status);
}
- *pagep = page;
- return status;
+ return folio;
+}
+EXPORT_SYMBOL(buffer_write_begin);
+
+int block_write_begin(struct address_space *mapping, loff_t pos, unsigned len,
+ struct page **pagep, get_block_t *get_block)
+{
+ struct folio *folio = buffer_write_begin(mapping, pos, len, get_block);
+
+ if (IS_ERR(folio))
+ return PTR_ERR(folio);
+ *pagep = &folio->page;
+ return 0;
}
EXPORT_SYMBOL(block_write_begin);
-int block_write_end(struct file *file, struct address_space *mapping,
- loff_t pos, unsigned len, unsigned copied,
- struct page *page, void *fsdata)
+size_t __buffer_write_end(struct file *file, struct address_space *mapping,
+ loff_t pos, size_t len, size_t copied, struct folio *folio)
{
- struct folio *folio = page_folio(page);
size_t start = pos - folio_pos(folio);
if (unlikely(copied < len)) {
@@ -2277,17 +2293,26 @@ int block_write_end(struct file *file, struct address_space *mapping,
return copied;
}
-EXPORT_SYMBOL(block_write_end);
+EXPORT_SYMBOL(__buffer_write_end);
-int generic_write_end(struct file *file, struct address_space *mapping,
+int block_write_end(struct file *file, struct address_space *mapping,
loff_t pos, unsigned len, unsigned copied,
struct page *page, void *fsdata)
+{
+ return buffer_write_end(file, mapping, pos, len, copied,
+ page_folio(page));
+}
+EXPORT_SYMBOL(block_write_end);
+
+size_t buffer_write_end(struct file *file, struct address_space *mapping,
+ loff_t pos, size_t len, size_t copied,
+ struct folio *folio)
{
struct inode *inode = mapping->host;
loff_t old_size = inode->i_size;
bool i_size_changed = false;
- copied = block_write_end(file, mapping, pos, len, copied, page, fsdata);
+ copied = __buffer_write_end(file, mapping, pos, len, copied, folio);
/*
* No need to use i_size_read() here, the i_size cannot change under us
@@ -2301,8 +2326,8 @@ int generic_write_end(struct file *file, struct address_space *mapping,
i_size_changed = true;
}
- unlock_page(page);
- put_page(page);
+ folio_unlock(folio);
+ folio_put(folio);
if (old_size < pos)
pagecache_isize_extended(inode, old_size, pos);
@@ -2316,6 +2341,15 @@ int generic_write_end(struct file *file, struct address_space *mapping,
mark_inode_dirty(inode);
return copied;
}
+EXPORT_SYMBOL(buffer_write_end);
+
+int generic_write_end(struct file *file, struct address_space *mapping,
+ loff_t pos, unsigned len, unsigned copied,
+ struct page *page, void *fsdata)
+{
+ return buffer_write_end(file, mapping, pos, len, copied,
+ page_folio(page));
+}
EXPORT_SYMBOL(generic_write_end);
/*
diff --git a/include/linux/buffer_head.h b/include/linux/buffer_head.h
index 1b7f14e39ab8..44e4b2b18cc0 100644
--- a/include/linux/buffer_head.h
+++ b/include/linux/buffer_head.h
@@ -267,6 +267,12 @@ int block_write_end(struct file *, struct address_space *,
int generic_write_end(struct file *, struct address_space *,
loff_t, unsigned, unsigned,
struct page *, void *);
+struct folio *buffer_write_begin(struct address_space *mapping, loff_t pos,
+ size_t len, get_block_t *get_block);
+size_t buffer_write_end(struct file *, struct address_space *, loff_t pos,
+ size_t len, size_t copied, struct folio *);
+size_t __buffer_write_end(struct file *, struct address_space *, loff_t pos,
+ size_t len, size_t copied, struct folio *);
void folio_zero_new_buffers(struct folio *folio, size_t from, size_t to);
int cont_write_begin(struct file *, struct address_space *, loff_t pos,
unsigned len, struct page **, void **fsdata, get_block_t *,
--
2.43.0
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