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| author | Ross Zwisler <zwisler@kernel.org> | 2018-09-11 20:31:16 +0300 |
|---|---|---|
| committer | Theodore Ts'o <tytso@mit.edu> | 2018-09-11 20:31:16 +0300 |
| commit | b1f382178d150f256c1cf95b9341fda6eb764459 (patch) | |
| tree | a0d4c289912c4150b948abd2729980d85d3e9ade /fs/ext4 | |
| parent | 5f8c10936fab2b69a487400f2872902e597dd320 (diff) | |
| download | linux-b1f382178d150f256c1cf95b9341fda6eb764459.tar.xz | |
ext4: close race between direct IO and ext4_break_layouts()
If the refcount of a page is lowered between the time that it is returned
by dax_busy_page() and when the refcount is again checked in
ext4_break_layouts() => ___wait_var_event(), the waiting function
ext4_wait_dax_page() will never be called. This means that
ext4_break_layouts() will still have 'retry' set to false, so we'll stop
looping and never check the refcount of other pages in this inode.
Instead, always continue looping as long as dax_layout_busy_page() gives us
a page which it found with an elevated refcount.
Signed-off-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Cc: stable@vger.kernel.org
Diffstat (limited to 'fs/ext4')
| -rw-r--r-- | fs/ext4/inode.c | 9 |
1 files changed, 3 insertions, 6 deletions
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c index 694f31364206..723058bfe43b 100644 --- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c @@ -4195,9 +4195,8 @@ int ext4_update_disksize_before_punch(struct inode *inode, loff_t offset, return 0; } -static void ext4_wait_dax_page(struct ext4_inode_info *ei, bool *did_unlock) +static void ext4_wait_dax_page(struct ext4_inode_info *ei) { - *did_unlock = true; up_write(&ei->i_mmap_sem); schedule(); down_write(&ei->i_mmap_sem); @@ -4207,14 +4206,12 @@ int ext4_break_layouts(struct inode *inode) { struct ext4_inode_info *ei = EXT4_I(inode); struct page *page; - bool retry; int error; if (WARN_ON_ONCE(!rwsem_is_locked(&ei->i_mmap_sem))) return -EINVAL; do { - retry = false; page = dax_layout_busy_page(inode->i_mapping); if (!page) return 0; @@ -4222,8 +4219,8 @@ int ext4_break_layouts(struct inode *inode) error = ___wait_var_event(&page->_refcount, atomic_read(&page->_refcount) == 1, TASK_INTERRUPTIBLE, 0, 0, - ext4_wait_dax_page(ei, &retry)); - } while (error == 0 && retry); + ext4_wait_dax_page(ei)); + } while (error == 0); return error; } |