From: Goldwyn Rodrigues <rgoldwyn@xxxxxxxx>
btrfs_write_check() checks for all parameters in one place before
beginning a write. This does away with inode_unlock() after every check.
In the later patches, it will help push inode_lock/unlock() in buffered
and direct write functions respectively.
Signed-off-by: Goldwyn Rodrigues <rgoldwyn@xxxxxxxx>
---
fs/btrfs/file.c | 160 +++++++++++++++++++++++++-----------------------
1 file changed, 82 insertions(+), 78 deletions(-)
diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
index f7e96754d4c9..61885b180c8c 100644
--- a/fs/btrfs/file.c
+++ b/fs/btrfs/file.c
@@ -1615,6 +1615,86 @@ void btrfs_check_nocow_unlock(struct btrfs_inode *inode)
btrfs_drew_write_unlock(&inode->root->snapshot_lock);
}
+static void update_time_for_write(struct inode *inode)
+{
+ struct timespec64 now;
+
+ if (IS_NOCMTIME(inode))
+ return;
+
+ now = current_time(inode);
+ if (!timespec64_equal(&inode->i_mtime, &now))
+ inode->i_mtime = now;
+
+ if (!timespec64_equal(&inode->i_ctime, &now))
+ inode->i_ctime = now;
+
+ if (IS_I_VERSION(inode))
+ inode_inc_iversion(inode);
+}
+
+static size_t btrfs_write_check(struct kiocb *iocb, struct iov_iter *from)
+{
+ struct file *file = iocb->ki_filp;
+ struct inode *inode = file_inode(file);
+ struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
+ loff_t pos = iocb->ki_pos;
+ size_t count = iov_iter_count(from);
+ int err;
+ loff_t oldsize;
+ loff_t start_pos;
+
+ err = generic_write_checks(iocb, from);
+ if (err <= 0)
+ return err;
+
+ if (iocb->ki_flags & IOCB_NOWAIT) {
+ size_t nocow_bytes = count;
+
+ /*
+ * We will allocate space in case nodatacow is not set,
+ * so bail
+ */
+ if (check_nocow_nolock(BTRFS_I(inode), pos, &nocow_bytes) <= 0)
+ return -EAGAIN;
+ /*
+ * There are holes in the range or parts of the range that must
+ * be COWed (shared extents, RO block groups, etc), so just bail
+ * out.
+ */
+ if (nocow_bytes < count)
+ return -EAGAIN;
+ }
+
+ current->backing_dev_info = inode_to_bdi(inode);
+ err = file_remove_privs(file);
+ if (err)
+ return err;
+
+ /*
+ * We reserve space for updating the inode when we reserve space for the
+ * extent we are going to write, so we will enospc out there. We don't
+ * need to start yet another transaction to update the inode as we will
+ * update the inode when we finish writing whatever data we write.
+ */
+ update_time_for_write(inode);
+
+ start_pos = round_down(pos, fs_info->sectorsize);
+ oldsize = i_size_read(inode);
+ if (start_pos > oldsize) {
+ /* Expand hole size to cover write data, preventing empty gap */
+ loff_t end_pos = round_up(pos + count,
+ fs_info->sectorsize);
+ err = btrfs_cont_expand(inode, oldsize, end_pos);
+ if (err) {
+ current->backing_dev_info = NULL;
+ return err;
+ }
+ }
+
+ return count;
+}
+
static noinline ssize_t btrfs_buffered_write(struct kiocb *iocb,
struct iov_iter *i)
{
@@ -1947,24 +2027,6 @@ static ssize_t btrfs_direct_write(struct kiocb *iocb, struct iov_iter *from)
return written ? written : err;
}
-static void update_time_for_write(struct inode *inode)
-{
- struct timespec64 now;
-
- if (IS_NOCMTIME(inode))
- return;
-
- now = current_time(inode);
- if (!timespec64_equal(&inode->i_mtime, &now))
- inode->i_mtime = now;
-
- if (!timespec64_equal(&inode->i_ctime, &now))
- inode->i_ctime = now;
-
- if (IS_I_VERSION(inode))
- inode_inc_iversion(inode);
-}
-
static ssize_t btrfs_file_write_iter(struct kiocb *iocb,
struct iov_iter *from)
{
@@ -1972,14 +2034,9 @@ static ssize_t btrfs_file_write_iter(struct kiocb *iocb,
struct inode *inode = file_inode(file);
struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
struct btrfs_root *root = BTRFS_I(inode)->root;
- u64 start_pos;
- u64 end_pos;
ssize_t num_written = 0;
const bool sync = iocb->ki_flags & IOCB_DSYNC;
ssize_t err;
- loff_t pos;
- size_t count;
- loff_t oldsize;
/*
* If BTRFS flips readonly due to some impossible error,
@@ -2000,65 +2057,12 @@ static ssize_t btrfs_file_write_iter(struct kiocb *iocb,
inode_lock(inode);
}
- err = generic_write_checks(iocb, from);
+ err = btrfs_write_check(iocb, from);
if (err <= 0) {
inode_unlock(inode);
return err;
}
- pos = iocb->ki_pos;
- count = iov_iter_count(from);
- if (iocb->ki_flags & IOCB_NOWAIT) {
- size_t nocow_bytes = count;
-
- /*
- * We will allocate space in case nodatacow is not set,
- * so bail
- */
- if (check_nocow_nolock(BTRFS_I(inode), pos, &nocow_bytes)
- <= 0) {
- inode_unlock(inode);
- return -EAGAIN;
- }
- /*
- * There are holes in the range or parts of the range that must
- * be COWed (shared extents, RO block groups, etc), so just bail
- * out.
- */
- if (nocow_bytes < count) {
- inode_unlock(inode);
- return -EAGAIN;
- }
- }
-
- current->backing_dev_info = inode_to_bdi(inode);
- err = file_remove_privs(file);
- if (err) {
- inode_unlock(inode);
- goto out;
- }
-
- /*
- * We reserve space for updating the inode when we reserve space for the
- * extent we are going to write, so we will enospc out there. We don't
- * need to start yet another transaction to update the inode as we will
- * update the inode when we finish writing whatever data we write.
- */
- update_time_for_write(inode);
-
- start_pos = round_down(pos, fs_info->sectorsize);
- oldsize = i_size_read(inode);
- if (start_pos > oldsize) {
- /* Expand hole size to cover write data, preventing empty gap */
- end_pos = round_up(pos + count,
- fs_info->sectorsize);
- err = btrfs_cont_expand(inode, oldsize, end_pos);
- if (err) {
- inode_unlock(inode);
- goto out;
- }
- }
-
if (sync)
atomic_inc(&BTRFS_I(inode)->sync_writers);
@@ -2116,7 +2120,7 @@ static ssize_t btrfs_file_write_iter(struct kiocb *iocb,
if (sync)
atomic_dec(&BTRFS_I(inode)->sync_writers);
-out:
+
current->backing_dev_info = NULL;
return num_written ? num_written : err;
}
--
2.26.2
