From 926d1650176448d7684b991fbe1a5b1a8289e97c Mon Sep 17 00:00:00 2001 From: Gao Xiang Date: Sun, 1 Dec 2019 16:01:09 +0800 Subject: [PATCH 1/2] erofs: zero out when listxattr is called with no xattr As David reported [1], ENODATA returns when attempting to modify files by using EROFS as an overlayfs lower layer. The root cause is that listxattr could return unexpected -ENODATA by mistake for inodes without xattr. That breaks listxattr return value convention and it can cause copy up failure when used with overlayfs. Resolve by zeroing out if no xattr is found for listxattr. [1] https://lore.kernel.org/r/CAEvUa7nxnby+rxK-KRMA46=exeOMApkDMAV08AjMkkPnTPV4CQ@mail.gmail.com Link: https://lore.kernel.org/r/20191201084040.29275-1-hsiangkao@aol.com Fixes: cadf1ccf1b00 ("staging: erofs: add error handling for xattr submodule") Cc: # 4.19+ Reviewed-by: Chao Yu Signed-off-by: Gao Xiang --- fs/erofs/xattr.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/fs/erofs/xattr.c b/fs/erofs/xattr.c index a13a78725c57..b766c3ee5fa8 100644 --- a/fs/erofs/xattr.c +++ b/fs/erofs/xattr.c @@ -649,6 +649,8 @@ ssize_t erofs_listxattr(struct dentry *dentry, struct listxattr_iter it; ret = init_inode_xattrs(d_inode(dentry)); + if (ret == -ENOATTR) + return 0; if (ret) return ret; From ffafde478309af01b2a495ecaf203125abfb35bd Mon Sep 17 00:00:00 2001 From: Gao Xiang Date: Sat, 7 Dec 2019 10:37:26 +0800 Subject: [PATCH 2/2] erofs: update documentation Some on-disk structures, fields have been renamed in v5.4, the corresponding document should be updated as well. Also fix misrespresentation of file time and words about fixed-sized output compression, data inline, etc. Link: https://lore.kernel.org/r/20191207025509.6614-1-hsiangkao@aol.com/ Signed-off-by: Gao Xiang --- Documentation/filesystems/erofs.txt | 27 ++++++++++++++------------- 1 file changed, 14 insertions(+), 13 deletions(-) diff --git a/Documentation/filesystems/erofs.txt b/Documentation/filesystems/erofs.txt index b0c085326e2e..db6d39c3ae71 100644 --- a/Documentation/filesystems/erofs.txt +++ b/Documentation/filesystems/erofs.txt @@ -24,11 +24,11 @@ Here is the main features of EROFS: - Metadata & data could be mixed by design; - 2 inode versions for different requirements: - v1 v2 + compact (v1) extended (v2) Inode metadata size: 32 bytes 64 bytes Max file size: 4 GB 16 EB (also limited by max. vol size) Max uids/gids: 65536 4294967296 - File creation time: no yes (64 + 32-bit timestamp) + File change time: no yes (64 + 32-bit timestamp) Max hardlinks: 65536 4294967296 Metadata reserved: 4 bytes 14 bytes @@ -39,7 +39,7 @@ Here is the main features of EROFS: - Support POSIX.1e ACLs by using xattrs; - Support transparent file compression as an option: - LZ4 algorithm with 4 KB fixed-output compression for high performance; + LZ4 algorithm with 4 KB fixed-sized output compression for high performance. The following git tree provides the file system user-space tools under development (ex, formatting tool mkfs.erofs): @@ -85,7 +85,7 @@ All data areas should be aligned with the block size, but metadata areas may not. All metadatas can be now observed in two different spaces (views): 1. Inode metadata space Each valid inode should be aligned with an inode slot, which is a fixed - value (32 bytes) and designed to be kept in line with v1 inode size. + value (32 bytes) and designed to be kept in line with compact inode size. Each inode can be directly found with the following formula: inode offset = meta_blkaddr * block_size + 32 * nid @@ -117,10 +117,10 @@ may not. All metadatas can be now observed in two different spaces (views): |-> aligned with 4B Inode could be 32 or 64 bytes, which can be distinguished from a common - field which all inode versions have -- i_advise: + field which all inode versions have -- i_format: __________________ __________________ - | i_advise | | i_advise | + | i_format | | i_format | |__________________| |__________________| | ... | | ... | | | | | @@ -129,12 +129,13 @@ may not. All metadatas can be now observed in two different spaces (views): |__________________| 64 bytes Xattrs, extents, data inline are followed by the corresponding inode with - proper alignes, and they could be optional for different data mappings, - _currently_ there are totally 3 valid data mappings supported: + proper alignment, and they could be optional for different data mappings. + _currently_ total 4 valid data mappings are supported: - 1) flat file data without data inline (no extent); - 2) fixed-output size data compression (must have extents); - 3) flat file data with tail-end data inline (no extent); + 0 flat file data without data inline (no extent); + 1 fixed-sized output data compression (with non-compacted indexes); + 2 flat file data with tail packing data inline (no extent); + 3 fixed-sized output data compression (with compacted indexes, v5.3+). The size of the optional xattrs is indicated by i_xattr_count in inode header. Large xattrs or xattrs shared by many different files can be @@ -182,8 +183,8 @@ introduce another on-disk field at all. Compression ----------- -Currently, EROFS supports 4KB fixed-output clustersize transparent file -compression, as illustrated below: +Currently, EROFS supports 4KB fixed-sized output transparent file compression, +as illustrated below: |---- Variant-Length Extent ----|-------- VLE --------|----- VLE ----- clusterofs clusterofs clusterofs