Nick Piggin <[EMAIL PROTECTED]> writes: > On Mon, Mar 12, 2007 at 11:55:30AM +0300, Dmitriy Monakhov wrote: >> Nick Piggin <[EMAIL PROTECTED]> writes: >> >> > On Mon, Mar 12, 2007 at 10:58:10AM +0300, Dmitriy Monakhov wrote: > >> >> @@ -2240,6 +2241,29 @@ ssize_t generic_file_aio_write(struct kiocb *iocb, >> >> const struct iovec *iov, >> >> mutex_lock(&inode->i_mutex); >> >> ret = __generic_file_aio_write_nolock(iocb, iov, nr_segs, >> >> &iocb->ki_pos); >> >> + /* >> >> + * If __generic_file_aio_write_nolock has failed. >> >> + * This may happen because of: >> >> + * 1) Bad segment found (failed before actual write attempt) >> >> + * 2) Segments are good, but actual write operation failed >> >> + * and may have instantiated a few blocks outside i_size. >> >> + * a) in case of buffered write these blocks was already >> >> + * trimmed by generic_file_buffered_write() >> >> + * b) in case of O_DIRECT these blocks weren't trimmed yet. >> >> + * >> >> + * In case of (2b) these blocks have to be trimmed off again. >> >> + */ >> >> + if (unlikely( ret < 0 && file->f_flags & O_DIRECT)) { >> >> + unsigned long nr_segs_avail = nr_segs; >> >> + size_t count = 0; >> >> + if (!generic_segment_checks(iov, &nr_segs_avail, &count, >> >> + VERIFY_READ)) { >> >> + /*It is (2b) case, because segments are good*/ >> >> + loff_t isize = i_size_read(inode); >> >> + if (pos + count > isize) >> >> + vmtruncate(inode, isize); >> >> + } >> >> + } >> > >> > OK, but wouldn't this be better to be done in the actual direct IO >> > functions themselves? Thus you could be sure that you have the 2b case, >> > and the code would be less fragile to something changing? >> Ohh, We can't just call vmtruncate() after generic_file_direct_write() >> failure while __generic_file_aio_write_nolock() becase where is no guarantee >> what i_mutex held. In fact all existing fs always invoke >> __generic_file_aio_write_nolock() with i_mutex held in case of S_ISREG files, >> but this was't explicitly demanded and documented. I've proposed to do it in >> previous versions of this patch, because it this just document current state >> of affairs, but David Chinner wasn't agree with it. > > It seemed like it was documented in the comments that you altered in this > patch... > > How would such a filesystem that did not hold i_mutex propose to fix the > problem? > > The burden should be on those filesystems that might not want to hold > i_mutex here, to solve the problem nicely, rather than generic code to take > this ugly code. Ok then what do you think about this version http://lkml.org/lkml/2006/12/18/103 witch was posted almost month ago :) > > - > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to [EMAIL PROTECTED] > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/
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