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Guard the inode write operation for readonly FS - #103
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Userspace ls command running on rv32emu emulated guestOS v6.18.x generates write traffic on the filesystem which is not typically expected and hangs the emulator to umount the simplefs disk. The readonly guardrail fixes the issue. [ 272.359329] Call Trace: [ 272.359512] [<c0009f54>] dump_backtrace+0x2c/0x3c [ 272.359921] [<c0001280>] show_stack+0x3c/0x50 [ 272.360256] [<c00057e0>] dump_stack_lvl+0x4c/0x74 [ 272.360634] [<c0005824>] dump_stack+0x1c/0x2c [ 272.360999] [<c01d3ec4>] submit_bio_noacct+0xd8/0x2e4 [ 272.361410] [<c01d41cc>] submit_bio+0xfc/0x10c [ 272.361795] [<c012d8d4>] submit_bh_wbc.isra.0+0x15c/0x178 [ 272.362240] [<c012d908>] submit_bh+0x18/0x28 [ 272.362637] [<c012da18>] __sync_dirty_buffer+0x84/0xc0 [ 272.363071] [<c012da70>] sync_dirty_buffer+0x1c/0x2c [ 272.363499] [<a40283b0>] simplefs_write_inode+0x108/0x138 [simplefs] [ 272.366368] [<c011d878>] __writeback_single_inode+0x1b0/0x1b4 [ 272.366789] [<c011da4c>] writeback_sb_inodes+0x1d0/0x3b4 [ 272.367192] [<c011dcb8>] __writeback_inodes_wb+0x88/0xe0 [ 272.367593] [<c011e078>] wb_writeback.isra.0+0x154/0x174 [ 272.367996] [<c011e7c4>] wb_workfn+0x168/0x28c [ 272.368372] [<c0028be0>] process_scheduled_works+0x1dc/0x294 [ 272.368774] [<c0028df0>] worker_thread+0x158/0x1e8 [ 272.369143] [<c0030760>] kthread+0x170/0x174 [ 272.369482] [<c0007cb8>] ret_from_fork_kernel+0x1c/0x74 [ 272.369898] [<c03e1e90>] ret_from_exception_end+0x1c/0x20
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This changes pass the simplefs boot test CI on rv32emu: https://github.com/sysprog21/rv32emu/actions/runs/42382983991/job/128438633546 Note that the CI status on rv32emu CI is fail, but actually they are the error of the virtio sound on Linux host and others. |
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Thank @ChinYikMing for contributing! |
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Nov 8, 2026
4f9e6dc2a2d1cdbe5a697ccb35c6c4d5c8926951 version fixes the write traffic when running userspace read command. [1] $ find /tmp/simplefs -type f -not -path '*/.git/*' -print0 | LC_ALL=C \ sort -z | xargs -0 sha1sum | LC_ALL=C sort | sha1sum [2] 12cee9d0095fbdf4bfcdae407fd30ae11bbfacef - [1] sysprog21/simplefs#103 [2] https://github.com/sysprog21/rv32emu/blob/ffb041bab9d1513e5329f25f486378778dceed13/mk/external.mk#L162
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Userspace ls command running on rv32emu emulated guestOS v6.18.x generates write traffic on the filesystem which is not typically expected and hangs the emulator to umount the simplefs disk.
The readonly guardrail fixes the issue.
Summary by cubic
Prevents simplefs writeback on read-only filesystems, which was hanging the emulator during umount when running
lson the guestOS.simplefs_write_inodenow returns early when the superblock is read-only, skipping the write path entirely.Written for commit feb243b. Summary will update on new commits.