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mm/readahead: add kerneldoc for read_pages

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Patch series "mm: document read_pages and simplify usage".

Add a kerneldoc for read_pages() to formalize an invariant and then use
it to simplify the callers in page_cache_ra_unbounded().


This patch (of 2):

Formalize one of the invariants provided by the current implementation so
that callers can depend on it, as discussed in [1].

Link: https://lore.kernel.org/all/20260501061146.6e61392d125cf1847d7cc181@linux-foundation.org/ [1]
Link: https://lore.kernel.org/20260512203154.754075-2-fmayle@google.com
Signed-off-by: Frederick Mayle <fmayle@google.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Frederick Mayle 2026-05-12 13:31:35 -07:00 committed by Andrew Morton
parent fd003fac7c
commit c516c365d9
1 changed files with 11 additions and 0 deletions
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11
mm/readahead.c
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@ -146,6 +146,17 @@ file_ra_state_init(struct file_ra_state *ra, struct address_space *mapping)
}
EXPORT_SYMBOL_GPL(file_ra_state_init);
/**
* read_pages() - Start IO for a contiguous range of allocated folios in the
* page cache.
* @rac: Readahead control.
*
* When read_pages() returns, it is guaranteed that all of the folios will have
* been processed or removed so that ``readahead_count(rac) == 0``. However,
* that does not imply that ``readahead_index(rac)`` will be updated to point
* to the end of the originally requested range because, for example, the
* filesystem may expand the range upwards.
*/
static void read_pages(struct readahead_control *rac)
{
const struct address_space_operations *aops = rac->mapping->a_ops;