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CVS commit: src/sys/fs/puffs

Module Name:    src
Committed By:   manu
Date:           Mon Aug 29 04:12:46 UTC 2011

Modified Files:
        src/sys/fs/puffs: puffs_node.c puffs_sys.h puffs_vnops.c

Log Message:
Add a mutex for operations that touch size (setattr, getattr, write, fsync).

This is required to avoid data corruption bugs, where a getattr slices
itself within a setattr operation, and sets the size to the stall value
it got from the filesystem. That value is smaller than the one set by
setattr, and the call to uvm_vnp_setsize() trigged a spurious truncate.
The result is a chunk of zeroed data in the file.

Such a situation can easily happen when the ioflush thread issue a
VOP_FSYNC/puffs_vnop_sync/flushvncache/dosetattrn while andother process
do a sys_stat/VOP_GETATTR/puffs_vnop_getattr.

This mutex on size operation can be removed the day we decide VOP_GETATTR
has to operated on a locked vnode, since the other operations that touch
size already require that.

To generate a diff of this commit:
cvs rdiff -u -r1.19 -r1.20 src/sys/fs/puffs/puffs_node.c
cvs rdiff -u -r1.77 -r1.78 src/sys/fs/puffs/puffs_sys.h
cvs rdiff -u -r1.154 -r1.155 src/sys/fs/puffs/puffs_vnops.c

Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.

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