diff options
Diffstat (limited to 'Documentation/filesystems')
| -rw-r--r-- | Documentation/filesystems/Locking | 11 | ||||
| -rw-r--r-- | Documentation/filesystems/vfs.txt | 8 |
2 files changed, 5 insertions, 14 deletions
diff --git a/Documentation/filesystems/Locking b/Documentation/filesystems/Locking index 75eea7ce3d7c..08086dc160d3 100644 --- a/Documentation/filesystems/Locking +++ b/Documentation/filesystems/Locking @@ -179,7 +179,6 @@ unlocks and drops the reference. prototypes: int (*writepage)(struct page *page, struct writeback_control *wbc); int (*readpage)(struct file *, struct page *); - int (*sync_page)(struct page *); int (*writepages)(struct address_space *, struct writeback_control *); int (*set_page_dirty)(struct page *page); int (*readpages)(struct file *filp, struct address_space *mapping, @@ -208,7 +207,6 @@ locking rules: PageLocked(page) i_mutex writepage: yes, unlocks (see below) readpage: yes, unlocks -sync_page: maybe writepages: set_page_dirty no readpages: @@ -226,8 +224,8 @@ error_remove_page: yes swap_activate: no swap_deactivate: no - ->write_begin(), ->write_end(), ->sync_page() and ->readpage() -may be called from the request handler (/dev/loop). + ->write_begin(), ->write_end() and ->readpage() may be called from +the request handler (/dev/loop). ->readpage() unlocks the page, either synchronously or via I/O completion. @@ -283,11 +281,6 @@ will leave the page itself marked clean but it will be tagged as dirty in the radix tree. This incoherency can lead to all sorts of hard-to-debug problems in the filesystem like having dirty inodes at umount and losing written data. - ->sync_page() locking rules are not well-defined - usually it is called -with lock on page, but that is not guaranteed. Considering the currently -existing instances of this method ->sync_page() itself doesn't look -well-defined... - ->writepages() is used for periodic writeback and for syscall-initiated sync operations. The address_space should start I/O against at least *nr_to_write pages. *nr_to_write must be decremented for each page which is diff --git a/Documentation/filesystems/vfs.txt b/Documentation/filesystems/vfs.txt index c61a223ef3ff..d4e07c00e18e 100644 --- a/Documentation/filesystems/vfs.txt +++ b/Documentation/filesystems/vfs.txt @@ -534,9 +534,7 @@ __sync_single_inode) to check if ->writepages has been successful in writing out the whole address_space. The Writeback tag is used by filemap*wait* and sync_page* functions, -via filemap_fdatawait_range, to wait for all writeback to -complete. While waiting ->sync_page (if defined) will be called on -each page that is found to require writeback. +via filemap_fdatawait_range, to wait for all writeback to complete. An address_space handler may attach extra information to a page, typically using the 'private' field in the 'struct page'. If such @@ -554,8 +552,8 @@ address_space has finer control of write sizes. The read process essentially only requires 'readpage'. The write process is more complicated and uses write_begin/write_end or -set_page_dirty to write data into the address_space, and writepage, -sync_page, and writepages to writeback data to storage. +set_page_dirty to write data into the address_space, and writepage +and writepages to writeback data to storage. Adding and removing pages to/from an address_space is protected by the inode's i_mutex. |