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| author | Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it> | 2005-09-03 15:54:55 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@evo.osdl.org> | 2005-09-05 00:05:45 -0700 |
| commit | d44ed4f86892e350f4b16a3489b7e7c1a9bb7ead (patch) | |
| tree | 19614a214c186c62ee6c5d3879392f6184f93e5b | |
| parent | 0abf40c1ac3f25d264c019e1cfe155d590defb87 (diff) | |
| download | lwn-d44ed4f86892e350f4b16a3489b7e7c1a9bb7ead.tar.gz lwn-d44ed4f86892e350f4b16a3489b7e7c1a9bb7ead.zip | |
[PATCH] shmem_populate: avoid an useless check, and some comments
Either shmem_getpage returns a failure, or it found a page, or it was told
it couldn't do any I/O. So it's useless to check nonblock in the else
branch. We could add a BUG() there but I preferred to comment the
offending function.
This was taken out from one Ingo Molnar's old patch I'm resurrecting.
Signed-off-by: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
| -rw-r--r-- | mm/filemap.c | 7 | ||||
| -rw-r--r-- | mm/shmem.c | 6 |
2 files changed, 12 insertions, 1 deletions
diff --git a/mm/filemap.c b/mm/filemap.c index edc54436fa94..88611928e71f 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -1504,8 +1504,12 @@ repeat: return -EINVAL; page = filemap_getpage(file, pgoff, nonblock); + + /* XXX: This is wrong, a filesystem I/O error may have happened. Fix that as + * done in shmem_populate calling shmem_getpage */ if (!page && !nonblock) return -ENOMEM; + if (page) { err = install_page(mm, vma, addr, page, prot); if (err) { @@ -1513,6 +1517,9 @@ repeat: return err; } } else { + /* No page was found just because we can't read it in now (being + * here implies nonblock != 0), but the page may exist, so set + * the PTE to fault it in later. */ err = install_file_pte(mm, vma, addr, pgoff, prot); if (err) return err; diff --git a/mm/shmem.c b/mm/shmem.c index 5a81b1ee4f7a..08a3bc2fba61 100644 --- a/mm/shmem.c +++ b/mm/shmem.c @@ -1195,6 +1195,7 @@ static int shmem_populate(struct vm_area_struct *vma, err = shmem_getpage(inode, pgoff, &page, sgp, NULL); if (err) return err; + /* Page may still be null, but only if nonblock was set. */ if (page) { mark_page_accessed(page); err = install_page(mm, vma, addr, page, prot); @@ -1202,7 +1203,10 @@ static int shmem_populate(struct vm_area_struct *vma, page_cache_release(page); return err; } - } else if (nonblock) { + } else { + /* No page was found just because we can't read it in + * now (being here implies nonblock != 0), but the page + * may exist, so set the PTE to fault it in later. */ err = install_file_pte(mm, vma, addr, pgoff, prot); if (err) return err; |