| From 9a9e106c3c12f046afcba89be3188601be682a93 Mon Sep 17 00:00:00 2001 |
| From: Sasha Levin <sashal@kernel.org> |
| Date: Tue, 5 Nov 2019 22:59:37 +1100 |
| Subject: ext4: iomap that extends beyond EOF should be marked dirty |
| |
| From: Matthew Bobrowski <mbobrowski@mbobrowski.org> |
| |
| [ Upstream commit 2e9b51d78229d5145725a481bb5464ebc0a3f9b2 ] |
| |
| 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: Sasha Levin <sashal@kernel.org> |
| --- |
| fs/ext4/inode.c | 8 +++++++- |
| 1 file changed, 7 insertions(+), 1 deletion(-) |
| |
| diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c |
| index 00d0c4b8fa30..950e3dcff7b0 100644 |
| --- a/fs/ext4/inode.c |
| +++ b/fs/ext4/inode.c |
| @@ -3544,8 +3544,14 @@ retry: |
| 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; |
| -- |
| 2.20.1 |
| |