btrfs: add an extra wait mode to read_extent_buffer_pages

read_extent_buffer_pages currently has two modes, either trigger a read
without waiting for anything, or wait for the I/O to finish. The former
also bails when it's unable to lock the page. This patch now adds an
additional parameter to allow it to block on page lock, but don't wait
for completion.

Changes v5:
 - merge the 2 wait parameters into one and define WAIT_NONE, WAIT_COMPLETE and
   WAIT_PAGE_LOCK

Change v6:
 - fix bug introduced in v5

Signed-off-by: Arne Jansen <sensille@gmx.net>

diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 07b3ac662e193e6b3a19180c3c3c9bfccbeb8028..e6170e142cad65fae6e7727e8bf89b617b41562d 100644 (file)
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -367,7 +367,8 @@ static int btree_read_extent_buffer_pages(struct btrfs_root *root,
        clear_bit(EXTENT_BUFFER_CORRUPT, &eb->bflags);
        io_tree = &BTRFS_I(root->fs_info->btree_inode)->io_tree;
        while (1) {
-               ret = read_extent_buffer_pages(io_tree, eb, start, 1,
+               ret = read_extent_buffer_pages(io_tree, eb, start,
+                                              WAIT_COMPLETE,
                                               btree_get_extent, mirror_num);
                if (!ret &&
                    !verify_parent_transid(io_tree, eb, parent_transid))
@@ -974,7 +975,7 @@ int readahead_tree_block(struct btrfs_root *root, u64 bytenr, u32 blocksize,
        if (!buf)
                return 0;
        read_extent_buffer_pages(&BTRFS_I(btree_inode)->io_tree,
-                                buf, 0, 0, btree_get_extent, 0);
+                                buf, 0, WAIT_NONE, btree_get_extent, 0);
        free_extent_buffer(buf);
        return ret;
 }

diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index d418164a35f134842ed3af4cfd5f43666b37c89d..823028e73cf813c8f19e28ba943a32613b21e98b 100644 (file)
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -3349,8 +3349,7 @@ int extent_buffer_uptodate(struct extent_io_tree *tree,
 }
 
 int read_extent_buffer_pages(struct extent_io_tree *tree,
-                            struct extent_buffer *eb,
-                            u64 start, int wait,
+                            struct extent_buffer *eb, u64 start, int wait,
                             get_extent_t *get_extent, int mirror_num)
 {
        unsigned long i;
@@ -3386,7 +3385,7 @@ int read_extent_buffer_pages(struct extent_io_tree *tree,
        num_pages = num_extent_pages(eb->start, eb->len);
        for (i = start_i; i < num_pages; i++) {
                page = extent_buffer_page(eb, i);
-               if (!wait) {
+               if (wait == WAIT_NONE) {
                        if (!trylock_page(page))
                                goto unlock_exit;
                } else {
@@ -3430,7 +3429,7 @@ int read_extent_buffer_pages(struct extent_io_tree *tree,
        if (bio)
                submit_one_bio(READ, bio, mirror_num, bio_flags);
 
-       if (ret || !wait)
+       if (ret || wait != WAIT_COMPLETE)
                return ret;
 
        for (i = start_i; i < num_pages; i++) {

diff --git a/fs/btrfs/extent_io.h b/fs/btrfs/extent_io.h
index 7b2f0c3e79292a2f73aec86ed112e46b1a438c69..6d74c6b346914573dd9de698acb19ab9d0d78dc5 100644 (file)
--- a/fs/btrfs/extent_io.h
+++ b/fs/btrfs/extent_io.h
@@ -248,6 +248,9 @@ struct extent_buffer *alloc_extent_buffer(struct extent_io_tree *tree,
 struct extent_buffer *find_extent_buffer(struct extent_io_tree *tree,
                                         u64 start, unsigned long len);
 void free_extent_buffer(struct extent_buffer *eb);
+#define WAIT_NONE      0
+#define WAIT_COMPLETE  1
+#define WAIT_PAGE_LOCK 2
 int read_extent_buffer_pages(struct extent_io_tree *tree,
                             struct extent_buffer *eb, u64 start, int wait,
                             get_extent_t *get_extent, int mirror_num);