Btrfs: __btrfs_buffered_write: Reserve/release extents aligned to block size

Currently, the code reserves/releases extents in multiples of PAGE_CACHE_SIZE
units. Fix this by doing reservation/releases in block size units.

Signed-off-by: Chandan Rajendra <chandan@linux.vnet.ibm.com>
Signed-off-by: David Sterba <dsterba@suse.com>

2 files changed, 33 insertions, 13 deletions

diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index a9496644f47d..ffb3617fad98 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -2353,6 +2353,9 @@ struct btrfs_map_token {
         unsigned long offset;
 };
 
+#define BTRFS_BYTES_TO_BLKS(fs_info, bytes) \
+                                ((bytes) >> (fs_info)->sb->s_blocksize_bits)
+
 static inline void btrfs_init_map_token (struct btrfs_map_token *token)
 {
         token->kaddr = NULL;
diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
index af782fdd4fca..9809557213d4 100644
--- a/fs/btrfs/file.c
+++ b/fs/btrfs/file.c
@@ -498,7 +498,7 @@ int btrfs_dirty_pages(struct btrfs_root *root, struct inode *inode,
         loff_t isize = i_size_read(inode);
 
         start_pos = pos & ~((u64)root->sectorsize - 1);
-        num_bytes = ALIGN(write_bytes + pos - start_pos, root->sectorsize);
+        num_bytes = round_up(write_bytes + pos - start_pos, root->sectorsize);
 
         end_of_last_block = start_pos + num_bytes - 1;
         err = btrfs_set_extent_delalloc(inode, start_pos, end_of_last_block,
@@ -1379,16 +1379,19 @@ fail:
 static noinline int
 lock_and_cleanup_extent_if_need(struct inode *inode, struct page **pages,
                                 size_t num_pages, loff_t pos,
+                                size_t write_bytes,
                                 u64 *lockstart, u64 *lockend,
                                 struct extent_state **cached_state)
 {
+        struct btrfs_root *root = BTRFS_I(inode)->root;
         u64 start_pos;
         u64 last_pos;
         int i;
         int ret = 0;
 
-        start_pos = pos & ~((u64)PAGE_CACHE_SIZE - 1);
-        last_pos = start_pos + ((u64)num_pages << PAGE_CACHE_SHIFT) - 1;
+        start_pos = round_down(pos, root->sectorsize);
+        last_pos = start_pos
+                + round_up(pos + write_bytes - start_pos, root->sectorsize) - 1;
 
         if (start_pos < inode->i_size) {
                 struct btrfs_ordered_extent *ordered;
@@ -1503,6 +1506,7 @@ static noinline ssize_t __btrfs_buffered_write(struct file *file,
 
         while (iov_iter_count(i) > 0) {
                 size_t offset = pos & (PAGE_CACHE_SIZE - 1);
+                size_t sector_offset;
                 size_t write_bytes = min(iov_iter_count(i),
                                          nrptrs * (size_t)PAGE_CACHE_SIZE -
                                          offset);
@@ -1511,6 +1515,8 @@ static noinline ssize_t __btrfs_buffered_write(struct file *file,
                 size_t reserve_bytes;
                 size_t dirty_pages;
                 size_t copied;
+                size_t dirty_sectors;
+                size_t num_sectors;
 
                 WARN_ON(num_pages > nrptrs);
 
@@ -1523,7 +1529,9 @@ static noinline ssize_t __btrfs_buffered_write(struct file *file,
                         break;
                 }
 
-                reserve_bytes = num_pages << PAGE_CACHE_SHIFT;
+                sector_offset = pos & (root->sectorsize - 1);
+                reserve_bytes = round_up(write_bytes + sector_offset,
+                                root->sectorsize);
 
                 if (BTRFS_I(inode)->flags & (BTRFS_INODE_NODATACOW |
                                              BTRFS_INODE_PREALLOC)) {
@@ -1542,7 +1550,9 @@ static noinline ssize_t __btrfs_buffered_write(struct file *file,
                                  */
                                 num_pages = DIV_ROUND_UP(write_bytes + offset,
                                                          PAGE_CACHE_SIZE);
-                                reserve_bytes = num_pages << PAGE_CACHE_SHIFT;
+                                reserve_bytes = round_up(write_bytes
+                                                        + sector_offset,
+                                                        root->sectorsize);
                                 goto reserve_metadata;
                         }
                 }
@@ -1576,8 +1586,8 @@ again:
                         break;
 
                 ret = lock_and_cleanup_extent_if_need(inode, pages, num_pages,
-                                                      pos, &lockstart, &lockend,
-                                                      &cached_state);
+                                                pos, write_bytes, &lockstart,
+                                                &lockend, &cached_state);
                 if (ret < 0) {
                         if (ret == -EAGAIN)
                                 goto again;
@@ -1612,9 +1622,16 @@ again:
                  * we still have an outstanding extent for the chunk we actually
                  * managed to copy.
                  */
-                if (num_pages > dirty_pages) {
-                        release_bytes = (num_pages - dirty_pages) <<
-                                PAGE_CACHE_SHIFT;
+                num_sectors = BTRFS_BYTES_TO_BLKS(root->fs_info,
+                                                reserve_bytes);
+                dirty_sectors = round_up(copied + sector_offset,
+                                        root->sectorsize);
+                dirty_sectors = BTRFS_BYTES_TO_BLKS(root->fs_info,
+                                                dirty_sectors);
+
+                if (num_sectors > dirty_sectors) {
+                        release_bytes = (write_bytes - copied)
+                                & ~((u64)root->sectorsize - 1);
                         if (copied > 0) {
                                 spin_lock(&BTRFS_I(inode)->lock);
                                 BTRFS_I(inode)->outstanding_extents++;
@@ -1633,7 +1650,8 @@ again:
                         }
                 }
 
-                release_bytes = dirty_pages << PAGE_CACHE_SHIFT;
+                release_bytes = round_up(copied + sector_offset,
+                                        root->sectorsize);
 
                 if (copied > 0)
                         ret = btrfs_dirty_pages(root, inode, pages,
@@ -1654,8 +1672,7 @@ again:
 
                 if (only_release_metadata && copied > 0) {
                         lockstart = round_down(pos, root->sectorsize);
-                        lockend = lockstart +
-                                (dirty_pages << PAGE_CACHE_SHIFT) - 1;
+                        lockend = round_up(pos + copied, root->sectorsize) - 1;
 
                         set_extent_bit(&BTRFS_I(inode)->io_tree, lockstart,
                                        lockend, EXTENT_NORESERVE, NULL,