diff options
Diffstat (limited to 'Documentation/filesystems')
| -rw-r--r-- | Documentation/filesystems/Locking | 7 | ||||
| -rw-r--r-- | Documentation/filesystems/configfs/configfs_example_explicit.c | 2 | ||||
| -rw-r--r-- | Documentation/filesystems/vfs.txt | 16 |
3 files changed, 18 insertions, 7 deletions
diff --git a/Documentation/filesystems/Locking b/Documentation/filesystems/Locking index a91f3089001..b6426f15b4a 100644 --- a/Documentation/filesystems/Locking +++ b/Documentation/filesystems/Locking @@ -173,12 +173,13 @@ prototypes: sector_t (*bmap)(struct address_space *, sector_t); int (*invalidatepage) (struct page *, unsigned long); int (*releasepage) (struct page *, int); + void (*freepage)(struct page *); int (*direct_IO)(int, struct kiocb *, const struct iovec *iov, loff_t offset, unsigned long nr_segs); int (*launder_page) (struct page *); locking rules: - All except set_page_dirty may block + All except set_page_dirty and freepage may block BKL PageLocked(page) i_mutex writepage: no yes, unlocks (see below) @@ -193,6 +194,7 @@ perform_write: no n/a yes bmap: no invalidatepage: no yes releasepage: no yes +freepage: no yes direct_IO: no launder_page: no yes @@ -288,6 +290,9 @@ buffers from the page in preparation for freeing it. It returns zero to indicate that the buffers are (or may be) freeable. If ->releasepage is zero, the kernel assumes that the fs has no private interest in the buffers. + ->freepage() is called when the kernel is done dropping the page +from the page cache. + ->launder_page() may be called prior to releasing a page if it is still found to be dirty. It returns zero if the page was successfully cleaned, or an error value if not. Note that in order to prevent the page diff --git a/Documentation/filesystems/configfs/configfs_example_explicit.c b/Documentation/filesystems/configfs/configfs_example_explicit.c index d428cc9f07f..fd53869f563 100644 --- a/Documentation/filesystems/configfs/configfs_example_explicit.c +++ b/Documentation/filesystems/configfs/configfs_example_explicit.c @@ -89,7 +89,7 @@ static ssize_t childless_storeme_write(struct childless *childless, char *p = (char *) page; tmp = simple_strtoul(p, &p, 10); - if (!p || (*p && (*p != '\n'))) + if ((*p != '\0') && (*p != '\n')) return -EINVAL; if (tmp > INT_MAX) diff --git a/Documentation/filesystems/vfs.txt b/Documentation/filesystems/vfs.txt index ed7e5efc06d..20899e095e7 100644 --- a/Documentation/filesystems/vfs.txt +++ b/Documentation/filesystems/vfs.txt @@ -534,6 +534,7 @@ struct address_space_operations { sector_t (*bmap)(struct address_space *, sector_t); int (*invalidatepage) (struct page *, unsigned long); int (*releasepage) (struct page *, int); + void (*freepage)(struct page *); ssize_t (*direct_IO)(int, struct kiocb *, const struct iovec *iov, loff_t offset, unsigned long nr_segs); struct page* (*get_xip_page)(struct address_space *, sector_t, @@ -660,11 +661,10 @@ struct address_space_operations { releasepage: releasepage is called on PagePrivate pages to indicate that the page should be freed if possible. ->releasepage should remove any private data from the page and clear the - PagePrivate flag. It may also remove the page from the - address_space. If this fails for some reason, it may indicate - failure with a 0 return value. - This is used in two distinct though related cases. The first - is when the VM finds a clean page with no active users and + PagePrivate flag. If releasepage() fails for some reason, it must + indicate failure with a 0 return value. + releasepage() is used in two distinct though related cases. The + first is when the VM finds a clean page with no active users and wants to make it a free page. If ->releasepage succeeds, the page will be removed from the address_space and become free. @@ -679,6 +679,12 @@ struct address_space_operations { need to ensure this. Possibly it can clear the PageUptodate bit if it cannot free private data yet. + freepage: freepage is called once the page is no longer visible in + the page cache in order to allow the cleanup of any private + data. Since it may be called by the memory reclaimer, it + should not assume that the original address_space mapping still + exists, and it should not block. + direct_IO: called by the generic read/write routines to perform direct_IO - that is IO requests which bypass the page cache and transfer data directly between the storage and the |