linux-ext4 - [PATCH 07/31] libext2fs: When writing a file that has a i_size > 2GB, set the large_file feature flag and update the superblock.

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Message-ID: <20131001012728.28415.89082.stgit@birch.djwong.org>
Date:	Mon, 30 Sep 2013 18:27:28 -0700
From:	"Darrick J. Wong" <darrick.wong@...cle.com>
To:	tytso@....edu, darrick.wong@...cle.com
Cc:	linux-ext4@...r.kernel.org
Subject: [PATCH 07/31] libext2fs: When writing a file that has a i_size > 2GB,
 set the large_file feature flag and update the superblock.

If someone tries to write a file that is larger than 2GB, we need to set the
large_file feature flag to affirm that i_size_hi can hold meaningful contents.
(I don't see anything checking large_file except e2fsck...)

Signed-off-by: Darrick J. Wong <darrick.wong@...cle.com>
---
 lib/ext2fs/fileio.c |   12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/lib/ext2fs/fileio.c b/lib/ext2fs/fileio.c
index 1f7002c..ae5cbf1 100644
--- a/lib/ext2fs/fileio.c
+++ b/lib/ext2fs/fileio.c
@@ -389,6 +389,18 @@ errcode_t ext2fs_file_set_size2(ext2_file_t file, ext2_off64_t size)
 	old_truncate = ((old_size + file->fs->blocksize - 1) >>
 		      EXT2_BLOCK_SIZE_BITS(file->fs->super)) + 1;

+	/* If we're writing a large file, set the large_file flag */
+	if (LINUX_S_ISREG(file->inode.i_mode) &&
+	    EXT2_I_SIZE(&file->inode) > 0x7FFFFFFULL &&
+	    (!EXT2_HAS_RO_COMPAT_FEATURE(file->fs->super,
+					 EXT2_FEATURE_RO_COMPAT_LARGE_FILE) ||
+	     file->fs->super->s_rev_level == EXT2_GOOD_OLD_REV)) {
+		file->fs->super->s_feature_ro_compat |=
+				EXT2_FEATURE_RO_COMPAT_LARGE_FILE;
+		ext2fs_update_dynamic_rev(file->fs);
+		ext2fs_mark_super_dirty(file->fs);
+	}
+
 	file->inode.i_size = size & 0xffffffff;
 	file->inode.i_size_high = (size >> 32);
 	if (file->ino) {

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