diff options
| -rw-r--r-- | fs/ext4/file.c | 25 |
1 files changed, 10 insertions, 15 deletions
diff --git a/fs/ext4/file.c b/fs/ext4/file.c index 2071b1e4322c..e99cc17b6bd2 100644 --- a/fs/ext4/file.c +++ b/fs/ext4/file.c @@ -476,6 +476,11 @@ restart: * required to change security info in file_modified(), for extending * I/O, any form of non-overwrite I/O, and unaligned I/O to unwritten * extents (as partial block zeroing may be required). + * + * Note that unaligned writes are allowed under shared lock so long as + * they are pure overwrites. Otherwise, concurrent unaligned writes risk + * data corruption due to partial block zeroing in the dio layer, and so + * the I/O must occur exclusively. */ if (*ilock_shared && ((!IS_NOSEC(inode) || *extend || !overwrite || @@ -492,21 +497,12 @@ restart: /* * Now that locking is settled, determine dio flags and exclusivity - * requirements. Unaligned writes are allowed under shared lock so long - * as they are pure overwrites. Set the iomap overwrite only flag as an - * added precaution in this case. Even though this is unnecessary, we - * can detect and warn on unexpected -EAGAIN if an unsafe unaligned - * write is ever submitted. - * - * Otherwise, concurrent unaligned writes risk data corruption due to - * partial block zeroing in the dio layer, and so the I/O must occur - * exclusively. The inode lock is already held exclusive if the write is - * non-overwrite or extending, so drain all outstanding dio and set the - * force wait dio flag. + * requirements. We don't use DIO_OVERWRITE_ONLY because we enforce + * behavior already. The inode lock is already held exclusive if the + * write is non-overwrite or extending, so drain all outstanding dio and + * set the force wait dio flag. */ - if (*ilock_shared && unaligned_io) { - *dio_flags = IOMAP_DIO_OVERWRITE_ONLY; - } else if (!*ilock_shared && (unaligned_io || *extend)) { + if (!*ilock_shared && (unaligned_io || *extend)) { if (iocb->ki_flags & IOCB_NOWAIT) { ret = -EAGAIN; goto out; @@ -608,7 +604,6 @@ static ssize_t ext4_dio_write_iter(struct kiocb *iocb, struct iov_iter *from) iomap_ops = &ext4_iomap_overwrite_ops; ret = iomap_dio_rw(iocb, from, iomap_ops, &ext4_dio_write_ops, dio_flags, NULL, 0); - WARN_ON_ONCE(ret == -EAGAIN && !(iocb->ki_flags & IOCB_NOWAIT)); if (ret == -ENOTBLK) ret = 0; |