erofs: fix blksize < PAGE_SIZE for file-backed mounts

Ian Kentrequested to merge
raven-au/centos-stream-10:RHEL-82421-file-backed-mounts into main

JIRA: https://issues.redhat.com/browse/RHEL-82421

Adjust sb->s_blocksize{,_bits} directly for file-backed mounts when the fs block size is smaller than PAGE_SIZE.

Previously, EROFS used sb_set_blocksize(), which caused a panic if bdev-backed mounts is not used.

Fixes: fb176750 ("erofs: add file-backed mount support")
Signed-off-by: Hongzhen Luo hongzhen@linux.alibaba.com
Link: https://lore.kernel.org/r/20241015103836.3757438-1-hongzhen@linux.alibaba.com
Signed-off-by: Gao Xiang hsiangkao@linux.alibaba.com

CVE: CVE-2024-56750
Signed-off-by: Ian Kent ikent@redhat.com

Edited by Ian Kent

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