kernel/fs/erofs/inode.c, branch master

erofs: allow sharing page cache with the same aops only

2026-02-23T10:04:18Z

Inode with identical data but different @aops cannot be mixed because the page cache is managed by different subsystems (e.g., @aops for compressed on-disk inodes cannot handle plain on-disk inodes). In this patch, we never allow inodes to share the page cache among plain, compressed, and fileio cases. When a shared inode is created, we initialize @aops that is the same as the initial real inode, and subsequent inodes cannot share the page cache if the inferred @aops differ from the corresponding shared inode. This is reasonable as a first step because, in typical use cases, if an inode is compressible, it will fall into compressed inodes across different filesystem images unless users use plain filesystems. However, in that cases, users will use plain filesystems all the time. Fixes: 5ef3208e3be5 ("erofs: introduce the page cache share feature") Signed-off-by: Hongbo Li Reviewed-by: Gao Xiang Signed-off-by: Gao Xiang

erofs: separate plain and compressed filesystems formally

2026-02-03T03:05:57Z

The EROFS on-disk format uses a tiny, plain metadata design that prioritizes performance and minimizes complex inconsistencies against common writable disk filesystems (almost all serious metadata inconsistency cannot happen in well-designed immutable filesystems like EROFS). EROFS deliberately avoids artificial design flaws to eliminate serious security risks from untrusted remote sources by design, although human-made implementation bugs can still happen sometimes. Currently, there is no strict check to prevent compressed inodes, especially LZ4-compressed inodes, from being read in plain filesystems. Starting with erofs-utils 1.0 and Linux 5.3, LZ4_0PADDING sb feature is automatically enabled for LZ4-compressed EROFS images to support in-place decompression. Furthermore, since Linux 5.4 LTS is no longer supported, we no longer need to handle ancient LZ4-compressed EROFS images generated by erofs-utils prior to 1.0. To formally distinguish different filesystem types for improved security: - Use the presence of LZ4_0PADDING or a non-zero `dsb->u1.lz4_max_distance` as a marker for compressed filesystems containing LZ4-compressed inodes only; - For other algorithms, use `dsb->u1.available_compr_algs` bitmap. Note: LZ4_0PADDING has been supported since Linux 5.4 (the first formal kernel version), so exposing it via sysfs is no longer necessary and is now deprecated (but remain it for five more years until 2031): `dsb->u1` has been strictly non-zero for all EROFS images containing compressed inodes starting with erofs-utils v1.3 and it is actually a much better marker for compressed filesystems. Signed-off-by: Gao Xiang

erofs: use inode_set_cached_link()

2026-02-03T03:05:47Z

Symlink lengths are now cached in in-memory inodes directly so that readlink can be sped up. Signed-off-by: Gao Xiang

erofs: mark inodes without acls in erofs_read_inode()

2026-01-28T07:38:37Z

Similar to commit 91ef18b567da ("ext4: mark inodes without acls in __ext4_iget()"), the ACL state won't be read when the file owner performs a lookup, and the RCU fast path for lookups won't work because the ACL state remains unknown. If there are no extended attributes, or if the xattr filter indicates that no ACL xattr is present, call cache_no_acl() directly. Reviewed-by: Hongbo Li Signed-off-by: Gao Xiang

erofs: support unencoded inodes for page cache share

2026-01-23T12:02:09Z

This patch adds inode page cache sharing functionality for unencoded files. I conducted experiments in the container environment. Below is the memory usage for reading all files in two different minor versions of container images: +-------------------+------------------+-------------+---------------+ | Image | Page Cache Share | Memory (MB) | Memory | | | | | Reduction (%) | +-------------------+------------------+-------------+---------------+ | | No | 241 | - | | redis +------------------+-------------+---------------+ | 7.2.4 & 7.2.5 | Yes | 163 | 33% | +-------------------+------------------+-------------+---------------+ | | No | 872 | - | | postgres +------------------+-------------+---------------+ | 16.1 & 16.2 | Yes | 630 | 28% | +-------------------+------------------+-------------+---------------+ | | No | 2771 | - | | tensorflow +------------------+-------------+---------------+ | 2.11.0 & 2.11.1 | Yes | 2340 | 16% | +-------------------+------------------+-------------+---------------+ | | No | 926 | - | | mysql +------------------+-------------+---------------+ | 8.0.11 & 8.0.12 | Yes | 735 | 21% | +-------------------+------------------+-------------+---------------+ | | No | 390 | - | | nginx +------------------+-------------+---------------+ | 7.2.4 & 7.2.5 | Yes | 219 | 44% | +-------------------+------------------+-------------+---------------+ | tomcat | No | 924 | - | | 10.1.25 & 10.1.26 +------------------+-------------+---------------+ | | Yes | 474 | 49% | +-------------------+------------------+-------------+---------------+ Additionally, the table below shows the runtime memory usage of the container: +-------------------+------------------+-------------+---------------+ | Image | Page Cache Share | Memory (MB) | Memory | | | | | Reduction (%) | +-------------------+------------------+-------------+---------------+ | | No | 35 | - | | redis +------------------+-------------+---------------+ | 7.2.4 & 7.2.5 | Yes | 28 | 20% | +-------------------+------------------+-------------+---------------+ | | No | 149 | - | | postgres +------------------+-------------+---------------+ | 16.1 & 16.2 | Yes | 95 | 37% | +-------------------+------------------+-------------+---------------+ | | No | 1028 | - | | tensorflow +------------------+-------------+---------------+ | 2.11.0 & 2.11.1 | Yes | 930 | 10% | +-------------------+------------------+-------------+---------------+ | | No | 155 | - | | mysql +------------------+-------------+---------------+ | 8.0.11 & 8.0.12 | Yes | 132 | 15% | +-------------------+------------------+-------------+---------------+ | | No | 25 | - | | nginx +------------------+-------------+---------------+ | 7.2.4 & 7.2.5 | Yes | 20 | 20% | +-------------------+------------------+-------------+---------------+ | tomcat | No | 186 | - | | 10.1.25 & 10.1.26 +------------------+-------------+---------------+ | | Yes | 98 | 48% | +-------------------+------------------+-------------+---------------+ Co-developed-by: Hongzhen Luo Signed-off-by: Hongzhen Luo Signed-off-by: Hongbo Li Reviewed-by: Gao Xiang Signed-off-by: Gao Xiang

erofs: add erofs_inode_set_aops helper to set the aops

2026-01-23T12:01:39Z

Add erofs_inode_set_aops helper to set the inode->i_mapping->a_ops and use IS_ENABLED to make it cleaner. Signed-off-by: Hongbo Li Reviewed-by: Gao Xiang Signed-off-by: Gao Xiang

Coccinelle-based conversion to use ->i_state accessors

2025-10-20T18:22:26Z

All places were patched by coccinelle with the default expecting that ->i_lock is held, afterwards entries got fixed up by hand to use unlocked variants as needed. The script: @@ expression inode, flags; @@ - inode->i_state & flags + inode_state_read(inode) & flags @@ expression inode, flags; @@ - inode->i_state &= ~flags + inode_state_clear(inode, flags) @@ expression inode, flag1, flag2; @@ - inode->i_state &= ~flag1 & ~flag2 + inode_state_clear(inode, flag1 | flag2) @@ expression inode, flags; @@ - inode->i_state |= flags + inode_state_set(inode, flags) @@ expression inode, flags; @@ - inode->i_state = flags + inode_state_assign(inode, flags) @@ expression inode, flags; @@ - flags = inode->i_state + flags = inode_state_read(inode) @@ expression inode, flags; @@ - READ_ONCE(inode->i_state) & flags + inode_state_read(inode) & flags Signed-off-by: Mateusz Guzik Signed-off-by: Christian Brauner

erofs: Add support for FS_IOC_GETFSLABEL

2025-09-25T03:26:20Z

Add support for reading to the erofs volume label from the FS_IOC_GETFSLABEL ioctls. Signed-off-by: Bo Liu (OpenAnolis) Reviewed-by: Gao Xiang Reviewed-by: Chao Yu Reviewed-by: Hongbo Li Signed-off-by: Gao Xiang

erofs: implement metadata compression

2025-07-24T11:43:31Z

Thanks to the meta buffer infrastructure, metadata-compressed inodes are just read from the metabox inode instead of the blockdevice (or backing file) inode. The same is true for shared extended attributes. When metadata compression is enabled, inode numbers are divided from on-disk NIDs because of non-LTS 32-bit application compatibility. Co-developed-by: Gao Xiang Signed-off-by: Bo Liu (OpenAnolis) Acked-by: Chao Yu Signed-off-by: Gao Xiang Link: https://lore.kernel.org/r/20250722003229.2121752-1-hsiangkao@linux.alibaba.com

erofs: remove need_kmap in erofs_read_metabuf()

2025-07-24T11:42:05Z

- need_kmap is always true except for a ztailpacking case; thus, just open-code that one; - The upcoming metadata compression will add a new boolean, so simplify this first. Signed-off-by: Gao Xiang Reviewed-by: Chao Yu Link: https://lore.kernel.org/r/20250714090907.4095645-1-hsiangkao@linux.alibaba.com