Merge git://git.kernel.org/pub/scm/linux/kernel/git/mason/btrfs-unstable

[mv-sheeva.git] / fs / btrfs / file.c

diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
index 7084140d5940e68f653ad8919a0084549d6b8e1b..f447b783bb84ce25af44cb2276b3d49684948166 100644 (file)
--- a/fs/btrfs/file.c
+++ b/fs/btrfs/file.c
@@ -70,6 +70,19 @@ static noinline int btrfs_copy_from_user(loff_t pos, int num_pages,
 
                /* Flush processor's dcache for this page */
                flush_dcache_page(page);
+
+               /*
+                * if we get a partial write, we can end up with
+                * partially up to date pages.  These add
+                * a lot of complexity, so make sure they don't
+                * happen by forcing this copy to be retried.
+                *
+                * The rest of the btrfs_file_write code will fall
+                * back to page at a time copies after we return 0.
+                */
+               if (!PageUptodate(page) && copied < count)
+                       copied = 0;
+
                iov_iter_advance(i, copied);
                write_bytes -= copied;
                total_copied += copied;
@@ -762,6 +775,27 @@ out:
        return 0;
 }
 
+/*
+ * on error we return an unlocked page and the error value
+ * on success we return a locked page and 0
+ */
+static int prepare_uptodate_page(struct page *page, u64 pos)
+{
+       int ret = 0;
+
+       if ((pos & (PAGE_CACHE_SIZE - 1)) && !PageUptodate(page)) {
+               ret = btrfs_readpage(NULL, page);
+               if (ret)
+                       return ret;
+               lock_page(page);
+               if (!PageUptodate(page)) {
+                       unlock_page(page);
+                       return -EIO;
+               }
+       }
+       return 0;
+}
+
 /*
  * 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
@@ -777,6 +811,7 @@ static noinline int prepare_pages(struct btrfs_root *root, struct file *file,
        unsigned long index = pos >> PAGE_CACHE_SHIFT;
        struct inode *inode = fdentry(file)->d_inode;
        int err = 0;
+       int faili = 0;
        u64 start_pos;
        u64 last_pos;
 
@@ -794,15 +829,24 @@ again:
        for (i = 0; i < num_pages; i++) {
                pages[i] = grab_cache_page(inode->i_mapping, index + i);
                if (!pages[i]) {
-                       int c;
-                       for (c = i - 1; c >= 0; c--) {
-                               unlock_page(pages[c]);
-                               page_cache_release(pages[c]);
-                       }
-                       return -ENOMEM;
+                       faili = i - 1;
+                       err = -ENOMEM;
+                       goto fail;
+               }
+
+               if (i == 0)
+                       err = prepare_uptodate_page(pages[i], pos);
+               if (i == num_pages - 1)
+                       err = prepare_uptodate_page(pages[i],
+                                                   pos + write_bytes);
+               if (err) {
+                       page_cache_release(pages[i]);
+                       faili = i - 1;
+                       goto fail;
                }
                wait_on_page_writeback(pages[i]);
        }
+       err = 0;
        if (start_pos < inode->i_size) {
                struct btrfs_ordered_extent *ordered;
                lock_extent_bits(&BTRFS_I(inode)->io_tree,
@@ -842,6 +886,14 @@ again:
                WARN_ON(!PageLocked(pages[i]));
        }
        return 0;
+fail:
+       while (faili >= 0) {
+               unlock_page(pages[faili]);
+               page_cache_release(pages[faili]);
+               faili--;
+       }
+       return err;
+
 }
 
 static ssize_t btrfs_file_aio_write(struct kiocb *iocb,
@@ -851,7 +903,6 @@ static ssize_t btrfs_file_aio_write(struct kiocb *iocb,
        struct file *file = iocb->ki_filp;
        struct inode *inode = fdentry(file)->d_inode;
        struct btrfs_root *root = BTRFS_I(inode)->root;
-       struct page *pinned[2];
        struct page **pages = NULL;
        struct iov_iter i;
        loff_t *ppos = &iocb->ki_pos;
@@ -872,9 +923,6 @@ static ssize_t btrfs_file_aio_write(struct kiocb *iocb,
        will_write = ((file->f_flags & O_DSYNC) || IS_SYNC(inode) ||
                      (file->f_flags & O_DIRECT));
 
-       pinned[0] = NULL;
-       pinned[1] = NULL;
-
        start_pos = pos;
 
        vfs_check_frozen(inode->i_sb, SB_FREEZE_WRITE);
@@ -962,32 +1010,6 @@ static ssize_t btrfs_file_aio_write(struct kiocb *iocb,
        first_index = pos >> PAGE_CACHE_SHIFT;
        last_index = (pos + iov_iter_count(&i)) >> PAGE_CACHE_SHIFT;
 
-       /*
-        * there are lots of better ways to do this, but this code
-        * makes sure the first and last page in the file range are
-        * up to date and ready for cow
-        */
-       if ((pos & (PAGE_CACHE_SIZE - 1))) {
-               pinned[0] = grab_cache_page(inode->i_mapping, first_index);
-               if (!PageUptodate(pinned[0])) {
-                       ret = btrfs_readpage(NULL, pinned[0]);
-                       BUG_ON(ret);
-                       wait_on_page_locked(pinned[0]);
-               } else {
-                       unlock_page(pinned[0]);
-               }
-       }
-       if ((pos + iov_iter_count(&i)) & (PAGE_CACHE_SIZE - 1)) {
-               pinned[1] = grab_cache_page(inode->i_mapping, last_index);
-               if (!PageUptodate(pinned[1])) {
-                       ret = btrfs_readpage(NULL, pinned[1]);
-                       BUG_ON(ret);
-                       wait_on_page_locked(pinned[1]);
-               } else {
-                       unlock_page(pinned[1]);
-               }
-       }
-
        while (iov_iter_count(&i) > 0) {
                size_t offset = pos & (PAGE_CACHE_SIZE - 1);
                size_t write_bytes = min(iov_iter_count(&i),
@@ -1024,8 +1046,20 @@ static ssize_t btrfs_file_aio_write(struct kiocb *iocb,
 
                copied = btrfs_copy_from_user(pos, num_pages,
                                           write_bytes, pages, &i);
-               dirty_pages = (copied + offset + PAGE_CACHE_SIZE - 1) >>
-                               PAGE_CACHE_SHIFT;
+
+               /*
+                * if we have trouble faulting in the pages, fall
+                * back to one page at a time
+                */
+               if (copied < write_bytes)
+                       nrptrs = 1;
+
+               if (copied == 0)
+                       dirty_pages = 0;
+               else
+                       dirty_pages = (copied + offset +
+                                      PAGE_CACHE_SIZE - 1) >>
+                                      PAGE_CACHE_SHIFT;
 
                if (num_pages > dirty_pages) {
                        if (copied > 0)
@@ -1069,10 +1103,6 @@ out:
                err = ret;
 
        kfree(pages);
-       if (pinned[0])
-               page_cache_release(pinned[0]);
-       if (pinned[1])
-               page_cache_release(pinned[1]);
        *ppos = pos;
 
        /*