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>
(cherry picked from commit bb82ab88dfdb12948af58989c75bfe904bc1b09d)

diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index dc03438025353b2a1a33b71fc267b4debed53073..8869846269a530ed86d4121882de5a049600fca9 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 78315f466ffdcca1882af2bdd6c9a860374d7e1f..9a83b2093619ddfa8f2eaed1eef6b7c498261887 100644 (file)
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -3725,8 +3725,7 @@ 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;
@@ -3762,7 +3761,7 @@ 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 {
@@ -3806,7 +3805,7 @@ 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 a8e20b6729227f4f469bc06b473fa5b7135a9be3..5d92fbe8ed9c5fe825768b0ca8156a6178e92e87 100644 (file)
--- a/fs/btrfs/extent_io.h
+++ b/fs/btrfs/extent_io.h
@@ -249,6 +249,9 @@ 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);