blob: 83f0d94bd27dac4eb6e67e0bcfc6310c849a1ddf [file] [log] [blame]
From e5146b1f82e1a5c65dfa917993d655709cdeab99 Mon Sep 17 00:00:00 2001
From: Matthew Bobrowski <mbobrowski@mbobrowski.org>
Date: Tue, 5 Nov 2019 22:59:37 +1100
Subject: [PATCH] ext4: iomap that extends beyond EOF should be marked dirty
commit 2e9b51d78229d5145725a481bb5464ebc0a3f9b2 upstream.
This patch addresses what Dave Chinner had discovered and fixed within
commit: 7684e2c4384d. This changes does not have any user visible
impact for ext4 as none of the current users of ext4_iomap_begin()
that extend files depend on IOMAP_F_DIRTY.
When doing a direct IO that spans the current EOF, and there are
written blocks beyond EOF that extend beyond the current write, the
only metadata update that needs to be done is a file size extension.
However, we don't mark such iomaps as IOMAP_F_DIRTY to indicate that
there is IO completion metadata updates required, and hence we may
fail to correctly sync file size extensions made in IO completion when
O_DSYNC writes are being used and the hardware supports FUA.
Hence when setting IOMAP_F_DIRTY, we need to also take into account
whether the iomap spans the current EOF. If it does, then we need to
mark it dirty so that IO completion will call generic_write_sync() to
flush the inode size update to stable storage correctly.
Signed-off-by: Matthew Bobrowski <mbobrowski@mbobrowski.org>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Ritesh Harjani <riteshh@linux.ibm.com>
Link: https://lore.kernel.org/r/8b43ee9ee94bee5328da56ba0909b7d2229ef150.1572949325.git.mbobrowski@mbobrowski.org
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 270e147d1392..3092b2ef0614 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -3568,8 +3568,14 @@ static int ext4_iomap_begin(struct inode *inode, loff_t offset, loff_t length,
return ret;
}
+ /*
+ * Writes that span EOF might trigger an I/O size update on completion,
+ * so consider them to be dirty for the purposes of O_DSYNC, even if
+ * there is no other metadata changes being made or are pending here.
+ */
iomap->flags = 0;
- if (ext4_inode_datasync_dirty(inode))
+ if (ext4_inode_datasync_dirty(inode) ||
+ offset + length > i_size_read(inode))
iomap->flags |= IOMAP_F_DIRTY;
iomap->bdev = inode->i_sb->s_bdev;
iomap->dax_dev = sbi->s_daxdev;
--
2.7.4