diff options
| author | Sheng Yong <shengyong1@xiaomi.com> | 2025-05-17 17:05:43 +0800 |
|---|---|---|
| committer | Gao Xiang <hsiangkao@linux.alibaba.com> | 2025-05-22 11:57:57 +0800 |
| commit | c36ec00d7f67590cb03e233959cd92fe969753a3 (patch) | |
| tree | 7120c2ae47c17c5027f4a2408e513359f96ca8b0 /fs/erofs/data.c | |
| parent | 12bf25d1659b1ec55e44fad2485155707062df79 (diff) | |
erofs: add 'fsoffset' mount option to specify filesystem offset
When attempting to use an archive file, such as APEX on android,
as a file-backed mount source, it fails because EROFS image within
the archive file does not start at offset 0. As a result, a loop
or a dm device is still needed to attach the image file at an
appropriate offset first. Similarly, if an EROFS image within a
block device does not start at offset 0, it cannot be mounted
directly either.
To address this issue, this patch adds a new mount option `fsoffset=x'
to accept a start offset for the primary device. The offset should be
aligned to the block size. EROFS will add this offset before performing
read requests.
Signed-off-by: Sheng Yong <shengyong1@xiaomi.com>
Signed-off-by: Wang Shuai <wangshuai12@xiaomi.com>
Reviewed-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Link: https://lore.kernel.org/r/20250517090544.2687651-1-shengyong1@xiaomi.com
[ Gao Xiang: minor update on documentation and the error message. ]
Reviewed-by: Hongbo Li <lihongbo22@huawei.com>
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Diffstat (limited to 'fs/erofs/data.c')
| -rw-r--r-- | fs/erofs/data.c | 5 |
1 files changed, 3 insertions, 2 deletions
diff --git a/fs/erofs/data.c b/fs/erofs/data.c index 2409d2ab0c28..6a329c329f43 100644 --- a/fs/erofs/data.c +++ b/fs/erofs/data.c @@ -27,7 +27,7 @@ void erofs_put_metabuf(struct erofs_buf *buf) void *erofs_bread(struct erofs_buf *buf, erofs_off_t offset, bool need_kmap) { - pgoff_t index = offset >> PAGE_SHIFT; + pgoff_t index = (buf->off + offset) >> PAGE_SHIFT; struct folio *folio = NULL; if (buf->page) { @@ -54,6 +54,7 @@ void erofs_init_metabuf(struct erofs_buf *buf, struct super_block *sb) struct erofs_sb_info *sbi = EROFS_SB(sb); buf->file = NULL; + buf->off = sbi->dif0.fsoff; if (erofs_is_fileio_mode(sbi)) { buf->file = sbi->dif0.file; /* some fs like FUSE needs it */ buf->mapping = buf->file->f_mapping; @@ -299,7 +300,7 @@ static int erofs_iomap_begin(struct inode *inode, loff_t offset, loff_t length, iomap->private = buf.base; } else { iomap->type = IOMAP_MAPPED; - iomap->addr = mdev.m_pa; + iomap->addr = mdev.m_dif->fsoff + mdev.m_pa; if (flags & IOMAP_DAX) iomap->addr += mdev.m_dif->dax_part_off; } |