Re: inode->i_dirty_buffers redundant ?

[V Ganesh <ganesh@veritas.com>]

Stephen C. Tweedie <sct@redhat.com> wrote:
: Hi,

: On Wed, Jan 24, 2001 at 03:25:16PM +0530, V Ganesh wrote:
:> now that we have inode->i_mapping->dirty_pages, what do we need
:> inode->i_dirty_buffers for ?

: Metadata.  Specifically, directory contents and indirection blocks.

: --Stephen

ah, mark_buffer_dirty_inode(). thanks.
so if I understand it,
1. read() and mmap read faults will put the page in i_mapping->clean_pages
2. mmaped writes will (eventually, from msync or unmap or swapout) put the
   page in i_mapping->dirty_pages
3. write() will put pages into i_dirty_buffers (__block_commit_write() calls
   buffer_insert_inode_queue()).

so i_dirty_buffers contains buffer_heads of pages coming from write() as
well as metadata buffers from mark_buffer_dirty_inode(). a dirty MAP_SHARED
page which has been write()n to will potentially exist in both lists.
won't doing a set_dirty_page() instead of buffer_insert_inode_queue() in
__block_commit_write() make things much simpler ? then we'd have i_dirty_buffers
having _only_ metadata, and all data pages in the i_mapping->*_pages lists.

ganesh
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