[PATCH v2 27/35] ubifs: alloc quota space in ubifs_write_begin

[Dongsheng Yang]

Besides inode, quota also limit the space. When
use want to write something, we have to tell quota
subsystem there is something is going to be written
into ubifs, please check the quota limit. If it exceed
the limit, return EQUOT. Else, record it and go on.

Signed-off-by: Dongsheng Yang <yangds.fnst at cn.fujitsu.com>
---
 fs/ubifs/file.c | 30 ++++++++++++++++++++++++++----
 1 file changed, 26 insertions(+), 4 deletions(-)

diff --git a/fs/ubifs/file.c b/fs/ubifs/file.c
index f307e86..b1e89ff 100644
--- a/fs/ubifs/file.c
+++ b/fs/ubifs/file.c
@@ -53,6 +53,7 @@
 #include <linux/mount.h>
 #include <linux/namei.h>
 #include <linux/slab.h>
+#include <linux/quotaops.h>
 
 int ubifs_read_block(struct inode *inode, void *addr, unsigned int block,
 		      struct ubifs_data_node *dn)
@@ -431,8 +432,10 @@ static int ubifs_write_begin(struct file *file, struct address_space *mapping,
 	struct ubifs_inode *ui = ubifs_inode(inode);
 	pgoff_t index = pos >> PAGE_CACHE_SHIFT;
 	int uninitialized_var(err), appending = !!(pos + len > inode->i_size);
+	int quota_size = 0;
 	int skipped_read = 0;
 	struct page *page;
+	int ret = 0;
 
 	ubifs_assert(ubifs_inode(inode)->ui_size == inode->i_size);
 	ubifs_assert(!c->ro_media && !c->ro_mount);
@@ -440,10 +443,22 @@ static int ubifs_write_begin(struct file *file, struct address_space *mapping,
 	if (unlikely(c->ro_error))
 		return -EROFS;
 
+	quota_size = ((pos + len) - inode->i_size);
+	if (quota_size < 0)
+		quota_size = 0;
+	if (S_ISREG(inode->i_mode)) {
+		dquot_initialize(inode);
+		ret = dquot_alloc_space_nodirty(inode, quota_size);
+		if (unlikely(ret))
+			goto err;
+	}
+
 	/* Try out the fast-path part first */
 	page = grab_cache_page_write_begin(mapping, index, flags);
-	if (unlikely(!page))
-		return -ENOMEM;
+	if (unlikely(!page)) {
+		ret = -ENOMEM;
+		goto free_quot;
+	}
 
 	if (!PageUptodate(page)) {
 		/* The page is not loaded from the flash */
@@ -497,7 +512,9 @@ static int ubifs_write_begin(struct file *file, struct address_space *mapping,
 		unlock_page(page);
 		page_cache_release(page);
 
-		return write_begin_slow(mapping, pos, len, pagep, flags);
+		ret = write_begin_slow(mapping, pos, len, pagep, flags);
+		if (unlikely(ret))
+			goto free_quot;
 	}
 
 	/*
@@ -507,7 +524,12 @@ static int ubifs_write_begin(struct file *file, struct address_space *mapping,
 	 * otherwise. This is an optimization (slightly hacky though).
 	 */
 	*pagep = page;
-	return 0;
+
+	return ret;
+free_quot:
+	dquot_free_space_nodirty(inode, quota_size);
+err:
+	return ret;
 
 }
 
-- 
1.8.4.2