On 2010-01-04, Lino Sanfilippo <lino.sanfili...@avira.com> wrote: > the reason for these kernel crashes is the use of the > generic_file_aio_write() kernel api. > > Using these genericXXX functions in the dazukofs file operations > is always dangerous, since they might require function definitions, that > are not provided (and not needed) by dazuko (i.e all kind of functions that > are called to physically write data to disk).
It is dangerous only if it is not what we want (or is being used incorrectly by us). I want to avoid copy/pasting code. > In this case generic_file_aio_write() marks the pages that belong to > the dazukofs inodes as dirty, which tells the kernel that they > should be written to disk. In turn the kernel calls the > write_begin() and writepage() functions of dazukofs address_space. > Note that these functions should never be called by the kernel, > since dazukofs does not write any data to disk itself. Agreed. They should not be called. I assume we are doing something wrong. > If we want dazukofs to provide functions for async write/read, we > have to do an own dazukofs wrapper (see dazukofs_mmap()) that checks > if the lower filesystem is prepared to handle these functions and if > so directs calls to the lower filesystem. I would prefer to know why generic_file_readonly_mmap() isn't working as we expect: as read-only. Perhaps we are simply using the generic functions incorrectly. DazukoFS is not the only filesystem that does not support mmap-writing. Others are jffs2, afs, 9p. John Ogness -- Dazuko Maintainer _______________________________________________ Dazuko-devel mailing list Dazuko-devel@nongnu.org http://lists.nongnu.org/mailman/listinfo/dazuko-devel
