diff options
| author | Ross Zwisler <ross.zwisler@linux.intel.com> | 2017-10-12 18:52:34 +0300 |
|---|---|---|
| committer | Theodore Ts'o <tytso@mit.edu> | 2017-10-12 18:52:34 +0300 |
| commit | 559db4c6d784ceedc2a5418ced4d357cb843e221 (patch) | |
| tree | be6a1f50c715af12510c45a7632a445efa4c1cd6 | |
| parent | 51e3ae81ec58e95f10a98ef3dd6d7bce5d8e35a2 (diff) | |
| download | linux-559db4c6d784ceedc2a5418ced4d357cb843e221.tar.xz | |
ext4: prevent data corruption with inline data + DAX
If an inode has inline data it is currently prevented from using DAX by a
check in ext4_set_inode_flags(). When the inode grows inline data via
ext4_create_inline_data() or removes its inline data via
ext4_destroy_inline_data_nolock(), the value of S_DAX can change.
Currently these changes are unsafe because we don't hold off page faults
and I/O, write back dirty radix tree entries and invalidate all mappings.
There are also issues with mm-level races when changing the value of S_DAX,
as well as issues with the VM_MIXEDMAP flag:
https://www.spinics.net/lists/linux-xfs/msg09859.html
The unsafe transition of S_DAX can reliably cause data corruption, as shown
by the following fstest:
https://patchwork.kernel.org/patch/9948381/
Fix this issue by preventing the DAX mount option from being used on
filesystems that were created to support inline data. Inline data is an
option given to mkfs.ext4.
Signed-off-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: Jan Kara <jack@suse.cz>
CC: stable@vger.kernel.org
| -rw-r--r-- | fs/ext4/inline.c | 10 | ||||
| -rw-r--r-- | fs/ext4/super.c | 5 |
2 files changed, 5 insertions, 10 deletions
diff --git a/fs/ext4/inline.c b/fs/ext4/inline.c index f0bbc8cb6555..1367553c43bb 100644 --- a/fs/ext4/inline.c +++ b/fs/ext4/inline.c @@ -303,11 +303,6 @@ static int ext4_create_inline_data(handle_t *handle, EXT4_I(inode)->i_inline_size = len + EXT4_MIN_INLINE_DATA_SIZE; ext4_clear_inode_flag(inode, EXT4_INODE_EXTENTS); ext4_set_inode_flag(inode, EXT4_INODE_INLINE_DATA); - /* - * Propagate changes to inode->i_flags as well - e.g. S_DAX may - * get cleared - */ - ext4_set_inode_flags(inode); get_bh(is.iloc.bh); error = ext4_mark_iloc_dirty(handle, inode, &is.iloc); @@ -452,11 +447,6 @@ static int ext4_destroy_inline_data_nolock(handle_t *handle, } } ext4_clear_inode_flag(inode, EXT4_INODE_INLINE_DATA); - /* - * Propagate changes to inode->i_flags as well - e.g. S_DAX may - * get set. - */ - ext4_set_inode_flags(inode); get_bh(is.iloc.bh); error = ext4_mark_iloc_dirty(handle, inode, &is.iloc); diff --git a/fs/ext4/super.c b/fs/ext4/super.c index b104096fce9e..986475c0d552 100644 --- a/fs/ext4/super.c +++ b/fs/ext4/super.c @@ -3708,6 +3708,11 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent) } if (sbi->s_mount_opt & EXT4_MOUNT_DAX) { + if (ext4_has_feature_inline_data(sb)) { + ext4_msg(sb, KERN_ERR, "Cannot use DAX on a filesystem" + " that may contain inline data"); + goto failed_mount; + } err = bdev_dax_supported(sb, blocksize); if (err) goto failed_mount; |