diff options
Diffstat (limited to 'fs/btrfs/file.c')
| -rw-r--r-- | fs/btrfs/file.c | 13 |
1 files changed, 9 insertions, 4 deletions
diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c index 36f51c311bb1..0b568c8d24cb 100644 --- a/fs/btrfs/file.c +++ b/fs/btrfs/file.c @@ -1039,7 +1039,6 @@ int btrfs_write_check(struct kiocb *iocb, size_t count) loff_t pos = iocb->ki_pos; int ret; loff_t oldsize; - loff_t start_pos; /* * Quickly bail out on NOWAIT writes if we don't have the nodatacow or @@ -1066,9 +1065,8 @@ int btrfs_write_check(struct kiocb *iocb, size_t count) inode_inc_iversion(inode); } - start_pos = round_down(pos, fs_info->sectorsize); oldsize = i_size_read(inode); - if (start_pos > oldsize) { + if (pos > oldsize) { /* Expand hole size to cover write data, preventing empty gap */ loff_t end_pos = round_up(pos + count, fs_info->sectorsize); @@ -1092,7 +1090,7 @@ ssize_t btrfs_buffered_write(struct kiocb *iocb, struct iov_iter *i) u64 lockend; size_t num_written = 0; ssize_t ret; - loff_t old_isize = i_size_read(inode); + loff_t old_isize; unsigned int ilock_flags = 0; const bool nowait = (iocb->ki_flags & IOCB_NOWAIT); unsigned int bdp_flags = (nowait ? BDP_ASYNC : 0); @@ -1105,6 +1103,13 @@ ssize_t btrfs_buffered_write(struct kiocb *iocb, struct iov_iter *i) if (ret < 0) return ret; + /* + * We can only trust the isize with inode lock held, or it can race with + * other buffered writes and cause incorrect call of + * pagecache_isize_extended() to overwrite existing data. + */ + old_isize = i_size_read(inode); + ret = generic_write_checks(iocb, i); if (ret <= 0) goto out; |