blackbird-op-linux/fs/overlayfs, branch master

ovl: fix lseek overflow on 32bit

2020-02-03T10:41:53+00:00

ovl_lseek() is using ssize_t to return the value from vfs_llseek(). On a 32-bit kernel ssize_t is a 32-bit signed int, which overflows above 2 GB. Assign the return value of vfs_llseek() to loff_t to fix this. Reported-by: Boris Gjenero Fixes: 9e46b840c705 ("ovl: support stacked SEEK_HOLE/SEEK_DATA") Cc: # v4.19 Signed-off-by: Miklos Szeredi

ovl: add splice file read write helper

2020-01-24T15:28:15+00:00

Now overlayfs falls back to use default file splice read and write, which is not compatiple with overlayfs, returning EFAULT. xfstests generic/591 can reproduce part of this. Tested this patch with xfstests auto group tests. Signed-off-by: Murphy Zhou Signed-off-by: Miklos Szeredi

ovl: implement async IO routines

2020-01-24T08:46:46+00:00

A performance regression was observed since linux v4.19 with aio test using fio with iodepth 128 on overlayfs. The queue depth of the device was always 1 which is unexpected. After investigation, it was found that commit 16914e6fc7e1 ("ovl: add ovl_read_iter()") and commit 2a92e07edc5e ("ovl: add ovl_write_iter()") resulted in vfs_iter_{read,write} being called on underlying filesystem, which always results in syncronous IO. Implement async IO for stacked reading and writing. This resolves the performance regresion. This is implemented by allocating a new kiocb for submitting the AIO request on the underlying filesystem. When the request is completed, the new kiocb is freed and the completion callback is called on the original iocb. Signed-off-by: Jiufei Xue Signed-off-by: Miklos Szeredi

ovl: layer is const

2020-01-24T08:46:45+00:00

The ovl_layer struct is never modified except at initialization. Signed-off-by: Miklos Szeredi

ovl: fix corner case of non-constant st_dev;st_ino

2020-01-24T08:46:45+00:00

On non-samefs overlay without xino, non pure upper inodes should use a pseudo_dev assigned to each unique lower fs, but if lower layer is on the same fs and upper layer, it has no pseudo_dev assigned. In this overlay layers setup: - two filesystems, A and B - upper layer is on A - lower layer 1 is also on A - lower layer 2 is on B Non pure upper overlay inode, whose origin is in layer 1 will have the st_dev;st_ino values of the real lower inode before copy up and the st_dev;st_ino values of the real upper inode after copy up. Fix this inconsitency by assigning a unique pseudo_dev also for upper fs, that will be used as st_dev value along with the lower inode st_dev for overlay inodes in the case above. Signed-off-by: Amir Goldstein Signed-off-by: Miklos Szeredi

ovl: fix corner case of conflicting lower layer uuid

2020-01-24T08:46:45+00:00

This fixes ovl_lower_uuid_ok() to correctly detect the corner case: - two filesystems, A and B, both have null uuid - upper layer is on A - lower layer 1 is also on A - lower layer 2 is on B In this case, bad_uuid would not have been set for B, because the check only involved the list of lower fs. Hence we'll try to decode a layer 2 origin on layer 1 and fail. We check for conflicting (and null) uuid among all lower layers, including those layers that are on the same fs as the upper layer. Reported-by: Miklos Szeredi Signed-off-by: Amir Goldstein Signed-off-by: Miklos Szeredi

ovl: generalize the lower_fs[] array

2020-01-24T08:46:45+00:00

Rename lower_fs[] array to fs[], extend its size by one and use index fsid (instead of fsid-1) to access the fs[] array. Initialize fs[0] with upper fs values. fsid 0 is reserved even with lower only overlay, so fs[0] remains null in this case. Signed-off-by: Amir Goldstein Signed-off-by: Miklos Szeredi

ovl: simplify ovl_same_sb() helper

2020-01-24T08:46:45+00:00

No code uses the sb returned from this helper, so make it retrun a boolean and rename it to ovl_same_fs(). The xino mode is irrelevant when all layers are on same fs, so instead of describing samefs with mode OVL_XINO_OFF, use a new xino_mode state, which is 0 in the case of samefs, -1 in the case of xino=off and > 0 with xino enabled. Create a new helper ovl_same_dev(), to use instead of the common check for (ovl_same_fs() || xinobits). Signed-off-by: Amir Goldstein Signed-off-by: Miklos Szeredi

ovl: generalize the lower_layers[] array

2020-01-22T19:11:41+00:00

Rename lower_layers[] array to layers[], extend its size by one and initialize layers[0] with upper layer values. Lower layers are now addressed with index 1..numlower. layers[0] is reserved even with lower only overlay. [SzM: replace ofs->numlower with ofs->numlayer, the latter's value is incremented by one] Signed-off-by: Amir Goldstein Signed-off-by: Miklos Szeredi

ovl: improving copy-up efficiency for big sparse file

2020-01-22T19:11:41+00:00

Current copy-up is not efficient for big sparse file, It's not only slow but also wasting more disk space when the target lower file has huge hole inside. This patch tries to recognize file hole and skip it during copy-up. Detail logic of hole detection as below: When we detect next data position is larger than current position we will skip that hole, otherwise we copy data in the size of OVL_COPY_UP_CHUNK_SIZE. Actually, it may not recognize all kind of holes and sometimes only skips partial of hole area. However, it will be enough for most of the use cases. Additionally, this optimization relies on lseek(2) SEEK_DATA implementation, so for some specific filesystems which do not support this feature will behave as before on copy-up. Reviewed-by: Amir Goldstein Signed-off-by: Chengguang Xu Signed-off-by: Miklos Szeredi