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| author | Curt Wohlgemuth <curtw@google.com> | 2012-03-05 10:40:22 -0500 |
|---|---|---|
| committer | Theodore Ts'o <tytso@mit.edu> | 2012-03-05 10:40:22 -0500 |
| commit | 4188188bdc3aed29eb41fb1537305cff7431d062 (patch) | |
| tree | 8068d261bb142eeb6b5c443db23baf1dca77b09e /fs/ext4/ext4.h | |
| parent | b43d17f319f2c502b17139d1cf70731b2b62c644 (diff) | |
| download | blackbird-obmc-linux-4188188bdc3aed29eb41fb1537305cff7431d062.tar.gz blackbird-obmc-linux-4188188bdc3aed29eb41fb1537305cff7431d062.zip | |
ext4: add comments to definition of ext4_io_end_t
This should make it more clear what this structure is used
for, and how some of the (mutually exclusive) fields are
used to keep page cache references.
Signed-off-by: Curt Wohlgemuth <curtw@google.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Diffstat (limited to 'fs/ext4/ext4.h')
| -rw-r--r-- | fs/ext4/ext4.h | 13 |
1 files changed, 10 insertions, 3 deletions
diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h index 37e7d8b66c99..26ee54b2ce82 100644 --- a/fs/ext4/ext4.h +++ b/fs/ext4/ext4.h @@ -194,18 +194,25 @@ struct ext4_io_page { #define MAX_IO_PAGES 128 +/* + * For converting uninitialized extents on a work queue. + * + * 'page' is only used from the writepage() path; 'pages' is only used for + * buffered writes; they are used to keep page references until conversion + * takes place. For AIO/DIO, neither field is filled in. + */ typedef struct ext4_io_end { struct list_head list; /* per-file finished IO list */ struct inode *inode; /* file being written to */ unsigned int flag; /* unwritten or not */ - struct page *page; /* page struct for buffer write */ + struct page *page; /* for writepage() path */ loff_t offset; /* offset in the file */ ssize_t size; /* size of the extent */ struct work_struct work; /* data work queue */ struct kiocb *iocb; /* iocb struct for AIO */ int result; /* error value for AIO */ - int num_io_pages; - struct ext4_io_page *pages[MAX_IO_PAGES]; + int num_io_pages; /* for writepages() */ + struct ext4_io_page *pages[MAX_IO_PAGES]; /* for writepages() */ } ext4_io_end_t; struct ext4_io_submit { |
