diff options
| -rw-r--r-- | fs/btrfs/direct-io.c | 43 |
1 files changed, 42 insertions, 1 deletions
diff --git a/fs/btrfs/direct-io.c b/fs/btrfs/direct-io.c index 88cb2e82a507..412309825d6f 100644 --- a/fs/btrfs/direct-io.c +++ b/fs/btrfs/direct-io.c @@ -15,10 +15,12 @@ struct btrfs_dio_data { ssize_t submitted; + loff_t old_isize; struct extent_changeset *data_reserved; struct btrfs_ordered_extent *ordered; bool data_space_reserved; bool nocow_done; + bool updated_isize; }; struct btrfs_dio_private { @@ -228,6 +230,7 @@ static int btrfs_get_blocks_direct_write(struct extent_map **map, bool space_reserved = false; u64 len = *lenp; u64 prev_len; + loff_t old_isize; int ret = 0; /* @@ -341,8 +344,14 @@ static int btrfs_get_blocks_direct_write(struct extent_map **map, * Need to update the i_size under the extent lock so buffered * readers will get the updated i_size when we unlock. */ - if (start + len > i_size_read(inode)) + old_isize = i_size_read(inode); + if (start + len > old_isize) { + if (!dio_data->updated_isize) { + dio_data->old_isize = old_isize; + dio_data->updated_isize = true; + } i_size_write(inode, start + len); + } out: if (ret && space_reserved) { btrfs_delalloc_release_extents(BTRFS_I(inode), len); @@ -626,6 +635,38 @@ static int btrfs_dio_iomap_end(struct inode *inode, loff_t pos, loff_t length, length -= submitted; if (write) { /* + * Got a short write and have updated the isize, need to + * revert the isize change. + * + * Normally we need to update isize with extent lock hold, + * but we're safe due to the following factors: + * + * - Only a single writer can be enlarging isize + * Enlarging isize will take the exclusive inode lock. + * + * - Buffered readers need to wait for the OE we're holding + * Buffered readers will lock extent and wait for OE + * of the folio range, and since page cache is invalidated + * the OE wait can not be skipped. + * + * So here we are safe to revert the isize before + * finishing the OE, and no reader of the remaining range + * can see the enlarged size. + * + * TODO: Extend the DIO_LOCKED lifespan for direct writes, + * and only enlarge isize after a successful write. + */ + if (dio_data->updated_isize) { + u64 new_isize; + + if (submitted == 0) + new_isize = dio_data->old_isize; + else + new_isize = max(dio_data->old_isize, pos); + i_size_write(inode, new_isize); + dio_data->updated_isize = false; + } + /* * We have a short write, if there is any range * that is submitted properly, that part will have * its own OE split from the original one. |