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    SubjectRe: Is nobh code still useful?
    On Thu 17-09-09 18:11:27, Boaz Harrosh wrote:
    > On 09/17/2009 04:56 PM, Jan Kara wrote:
    > > Hi,
    > >
    > > during my page_mkwrite() work, I've looked at who uses nobh_ versions of
    > > various functions in fs/buffer.c. It seems only ext2 and jfs use them. ext3
    > > uses them only from writepage() (which means we needn't attach buffers to a
    > > page when it was written via mmap in writeback mode) and ext4 tries to use
    > > them but in fact it's nop because it always attaches buffers to the page
    > > earlier. So it's not really widely used, there's quite some code to support
    > > it (including one page flag), and it also slightly complicates my
    > > page_mkwrite() fixes.
    > > So I wanted to ask does somebody actually remember what it is good for?
    > > Buffer heads obviously consume some memory so was that the reason? OTOH we
    > > have to map the page whenever we write to it or send it to disk via
    > > writepage().
    > >
    > > Honza
    > I'm currently using nobh_truncate_page() in fs/exofs/inode.c::exofs_truncate().
    > Though, I suspect that once I do the conversion to Nick's:
    > "[patch 00/11] new truncate sequence"
    > and it is submitted, that use will disappear.
    Yeah, actually with page_mkwrite patches I've just sent, this would
    definitely go away so this isn't a use I'm too much worried about ;). But
    thanks for info anyway.

    Jan Kara <>
    SUSE Labs, CR

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