linux-ext4 - [PATCH 31/74] libext2fs: fail fileio write if we can't allocate a block

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Date:	Tue, 10 Dec 2013 17:21:47 -0800
From:	"Darrick J. Wong" <darrick.wong@...cle.com>
To:	tytso@....edu, darrick.wong@...cle.com
Cc:	linux-ext4@...r.kernel.org
Subject: [PATCH 31/74] libext2fs: fail fileio write if we can't allocate a
 block

If we're using ext2fs_file_write() to write to a hole in a file,
ensure that we can actually allocate the block before updating i_size.
In other words, don't update i_size and don't return success if we hit
an error while allocating space.

Signed-off-by: Darrick J. Wong <darrick.wong@...cle.com>
---
 lib/ext2fs/fileio.c |   14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/lib/ext2fs/fileio.c b/lib/ext2fs/fileio.c
index d092e65..03bdf86 100644
--- a/lib/ext2fs/fileio.c
+++ b/lib/ext2fs/fileio.c
@@ -297,6 +297,20 @@ errcode_t ext2fs_file_write(ext2_file_t file, const void *buf,
 		if (retval)
 			goto fail;

+		/*
+		 * OK, the physical block hasn't been allocated yet.
+		 * Allocate it.
+		 */
+		if (!file->physblock) {
+			retval = ext2fs_bmap2(fs, file->ino, &file->inode,
+					      BMAP_BUFFER,
+					      file->ino ? BMAP_ALLOC : 0,
+					      file->blockno, 0,
+					      &file->physblock);
+			if (retval)
+				goto fail;
+		}
+
 		file->flags |= EXT2_FILE_BUF_DIRTY;
 		memcpy(file->buf+start, ptr, c);
 		file->pos += c;

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