diff options
Diffstat (limited to 'fs/btrfs/file.c')
| -rw-r--r-- | fs/btrfs/file.c | 44 |
1 files changed, 43 insertions, 1 deletions
diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c index 1b7e51a9db0..3088a118448 100644 --- a/fs/btrfs/file.c +++ b/fs/btrfs/file.c @@ -41,6 +41,9 @@ #include "compat.h" +/* simple helper to fault in pages and copy. This should go away + * and be replaced with calls into generic code. + */ static int noinline btrfs_copy_from_user(loff_t pos, int num_pages, int write_bytes, struct page **prepared_pages, @@ -72,12 +75,19 @@ static int noinline btrfs_copy_from_user(loff_t pos, int num_pages, return page_fault ? -EFAULT : 0; } +/* + * unlocks pages after btrfs_file_write is done with them + */ static void noinline btrfs_drop_pages(struct page **pages, size_t num_pages) { size_t i; for (i = 0; i < num_pages; i++) { if (!pages[i]) break; + /* page checked is some magic around finding pages that + * have been modified without going through btrfs_set_page_dirty + * clear it here + */ ClearPageChecked(pages[i]); unlock_page(pages[i]); mark_page_accessed(pages[i]); @@ -85,6 +95,10 @@ static void noinline btrfs_drop_pages(struct page **pages, size_t num_pages) } } +/* this does all the hard work for inserting an inline extent into + * the btree. Any existing inline extent is extended as required to make room, + * otherwise things are inserted as required into the btree + */ static int noinline insert_inline_extent(struct btrfs_trans_handle *trans, struct btrfs_root *root, struct inode *inode, u64 offset, size_t size, @@ -228,6 +242,14 @@ fail: return err; } +/* + * after copy_from_user, pages need to be dirtied and we need to make + * sure holes are created between the current EOF and the start of + * any next extents (if required). + * + * this also makes the decision about creating an inline extent vs + * doing real data extents, marking pages dirty and delalloc as required. + */ static int noinline dirty_and_release_pages(struct btrfs_trans_handle *trans, struct btrfs_root *root, struct file *file, @@ -362,6 +384,10 @@ out_unlock: return err; } +/* + * this drops all the extents in the cache that intersect the range + * [start, end]. Existing extents are split as required. + */ int btrfs_drop_extent_cache(struct inode *inode, u64 start, u64 end, int skip_pinned) { @@ -536,6 +562,9 @@ out: * If an extent intersects the range but is not entirely inside the range * it is either truncated or split. Anything entirely inside the range * is deleted from the tree. + * + * inline_limit is used to tell this code which offsets in the file to keep + * if they contain inline extents. */ int noinline btrfs_drop_extents(struct btrfs_trans_handle *trans, struct btrfs_root *root, struct inode *inode, @@ -796,7 +825,9 @@ out: } /* - * this gets pages into the page cache and locks them down + * this gets pages into the page cache and locks them down, it also properly + * waits for data=ordered extents to finish before allowing the pages to be + * modified. */ static int noinline prepare_pages(struct btrfs_root *root, struct file *file, struct page **pages, size_t num_pages, @@ -1034,6 +1065,17 @@ int btrfs_release_file(struct inode * inode, struct file * filp) return 0; } +/* + * fsync call for both files and directories. This logs the inode into + * the tree log instead of forcing full commits whenever possible. + * + * It needs to call filemap_fdatawait so that all ordered extent updates are + * in the metadata btree are up to date for copying to the log. + * + * It drops the inode mutex before doing the tree log commit. This is an + * important optimization for directories because holding the mutex prevents + * new operations on the dir while we write to disk. + */ int btrfs_sync_file(struct file *file, struct dentry *dentry, int datasync) { struct inode *inode = dentry->d_inode; |