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3f4aa98181
When doing a partial writeback, afs_write_back_from_locked_page() may
generate an FS.StoreData RPC request that writes out part of a file when a
file has been constructed from pieces by doing seek, write, seek, write,
... as is done by ld.
The FS.StoreData RPC is given the current i_size as the file length, but
the server basically ignores it unless the data length is 0 (in which case
it's just a truncate operation). The revised file length returned in the
result of the RPC may then not reflect what we suggested - and this leads
to i_size getting moved backwards - which causes issues later.
Fix the client to take account of this by ignoring the returned file size
unless the data version number jumped unexpectedly - in which case we're
going to have to clear the pagecache and reload anyway.
This can be observed when doing a kernel build on an AFS mount. The
following pair of commands produce the issue:
ld -m elf_x86_64 -z max-page-size=0x200000 --emit-relocs \
-T arch/x86/realmode/rm/realmode.lds \
arch/x86/realmode/rm/header.o \
arch/x86/realmode/rm/trampoline_64.o \
arch/x86/realmode/rm/stack.o \
arch/x86/realmode/rm/reboot.o \
-o arch/x86/realmode/rm/realmode.elf
arch/x86/tools/relocs --realmode \
arch/x86/realmode/rm/realmode.elf \
>arch/x86/realmode/rm/realmode.relocs
This results in the latter giving:
Cannot read ELF section headers 0/18: Success
as the realmode.elf file got corrupted.
The sequence of events can also be driven with:
xfs_io -t -f \
-c "pwrite -S 0x58 0 0x58" \
-c "pwrite -S 0x59 10000 1000" \
-c "close" \
/afs/example.com/scratch/a
Fixes:
|
||
|---|---|---|
| .. | ||
| addr_list.c | ||
| afs_cm.h | ||
| afs_fs.h | ||
| afs_vl.h | ||
| afs.h | ||
| cache.c | ||
| callback.c | ||
| cell.c | ||
| cmservice.c | ||
| dir_edit.c | ||
| dir_silly.c | ||
| dir.c | ||
| dynroot.c | ||
| file.c | ||
| flock.c | ||
| fs_operation.c | ||
| fs_probe.c | ||
| fsclient.c | ||
| inode.c | ||
| internal.h | ||
| Kconfig | ||
| main.c | ||
| Makefile | ||
| misc.c | ||
| mntpt.c | ||
| proc.c | ||
| protocol_uae.h | ||
| protocol_yfs.h | ||
| rotate.c | ||
| rxrpc.c | ||
| security.c | ||
| server_list.c | ||
| server.c | ||
| super.c | ||
| vl_alias.c | ||
| vl_list.c | ||
| vl_probe.c | ||
| vl_rotate.c | ||
| vlclient.c | ||
| volume.c | ||
| write.c | ||
| xattr.c | ||
| xdr_fs.h | ||
| yfsclient.c | ||