| Message ID | 153374915981.40645.3350205963852459041.stgit@djiang5-desk3.ch.intel.com |
|---|---|
| State | Not Applicable |
| Headers | show |
| Series | [v2,1/2] ext4: Close race between direct IO and ext4_break_layouts() | expand |
On Wed 08-08-18 10:26:36, Dave Jiang wrote: > This patch is the duplicate of ross's fix for ext4 for xfs. > > 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 > xfs_break_layouts() => ___wait_var_event(), the waiting function > xfs_wait_dax_page() will never be called. This means that > xfs_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: Dave Jiang <dave.jiang@intel.com> I think I gave you my reviewed-by tag already for the previous version. But here it is again: Reviewed-by: Jan Kara <jack@suse.cz> Honza > --- > > v2: > - Rename parameter from did_unlock to retry (Jan) > > fs/xfs/xfs_file.c | 9 ++++----- > 1 file changed, 4 insertions(+), 5 deletions(-) > > diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c > index a3e7767a5715..cd6f0d8c4922 100644 > --- a/fs/xfs/xfs_file.c > +++ b/fs/xfs/xfs_file.c > @@ -721,12 +721,10 @@ xfs_file_write_iter( > > static void > xfs_wait_dax_page( > - struct inode *inode, > - bool *did_unlock) > + struct inode *inode) > { > struct xfs_inode *ip = XFS_I(inode); > > - *did_unlock = true; > xfs_iunlock(ip, XFS_MMAPLOCK_EXCL); > schedule(); > xfs_ilock(ip, XFS_MMAPLOCK_EXCL); > @@ -736,7 +734,7 @@ static int > xfs_break_dax_layouts( > struct inode *inode, > uint iolock, > - bool *did_unlock) > + bool *retry) > { > struct page *page; > > @@ -746,9 +744,10 @@ xfs_break_dax_layouts( > if (!page) > return 0; > > + *retry = true; > return ___wait_var_event(&page->_refcount, > atomic_read(&page->_refcount) == 1, TASK_INTERRUPTIBLE, > - 0, 0, xfs_wait_dax_page(inode, did_unlock)); > + 0, 0, xfs_wait_dax_page(inode)); > } > > int >
On 08/09/2018 01:57 AM, Jan Kara wrote: > On Wed 08-08-18 10:26:36, Dave Jiang wrote: >> This patch is the duplicate of ross's fix for ext4 for xfs. >> >> 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 >> xfs_break_layouts() => ___wait_var_event(), the waiting function >> xfs_wait_dax_page() will never be called. This means that >> xfs_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: Dave Jiang <dave.jiang@intel.com> > > I think I gave you my reviewed-by tag already for the previous version. But > here it is again: > > Reviewed-by: Jan Kara <jack@suse.cz> Yes you did. I forgot to append it when I sent it out the first time. I resent it. :) > > Honza > >> --- >> >> v2: >> - Rename parameter from did_unlock to retry (Jan) >> >> fs/xfs/xfs_file.c | 9 ++++----- >> 1 file changed, 4 insertions(+), 5 deletions(-) >> >> diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c >> index a3e7767a5715..cd6f0d8c4922 100644 >> --- a/fs/xfs/xfs_file.c >> +++ b/fs/xfs/xfs_file.c >> @@ -721,12 +721,10 @@ xfs_file_write_iter( >> >> static void >> xfs_wait_dax_page( >> - struct inode *inode, >> - bool *did_unlock) >> + struct inode *inode) >> { >> struct xfs_inode *ip = XFS_I(inode); >> >> - *did_unlock = true; >> xfs_iunlock(ip, XFS_MMAPLOCK_EXCL); >> schedule(); >> xfs_ilock(ip, XFS_MMAPLOCK_EXCL); >> @@ -736,7 +734,7 @@ static int >> xfs_break_dax_layouts( >> struct inode *inode, >> uint iolock, >> - bool *did_unlock) >> + bool *retry) >> { >> struct page *page; >> >> @@ -746,9 +744,10 @@ xfs_break_dax_layouts( >> if (!page) >> return 0; >> >> + *retry = true; >> return ___wait_var_event(&page->_refcount, >> atomic_read(&page->_refcount) == 1, TASK_INTERRUPTIBLE, >> - 0, 0, xfs_wait_dax_page(inode, did_unlock)); >> + 0, 0, xfs_wait_dax_page(inode)); >> } >> >> int >>
diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c index a3e7767a5715..cd6f0d8c4922 100644 --- a/fs/xfs/xfs_file.c +++ b/fs/xfs/xfs_file.c @@ -721,12 +721,10 @@ xfs_file_write_iter( static void xfs_wait_dax_page( - struct inode *inode, - bool *did_unlock) + struct inode *inode) { struct xfs_inode *ip = XFS_I(inode); - *did_unlock = true; xfs_iunlock(ip, XFS_MMAPLOCK_EXCL); schedule(); xfs_ilock(ip, XFS_MMAPLOCK_EXCL); @@ -736,7 +734,7 @@ static int xfs_break_dax_layouts( struct inode *inode, uint iolock, - bool *did_unlock) + bool *retry) { struct page *page; @@ -746,9 +744,10 @@ xfs_break_dax_layouts( if (!page) return 0; + *retry = true; return ___wait_var_event(&page->_refcount, atomic_read(&page->_refcount) == 1, TASK_INTERRUPTIBLE, - 0, 0, xfs_wait_dax_page(inode, did_unlock)); + 0, 0, xfs_wait_dax_page(inode)); } int
This patch is the duplicate of ross's fix for ext4 for xfs. 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 xfs_break_layouts() => ___wait_var_event(), the waiting function xfs_wait_dax_page() will never be called. This means that xfs_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: Dave Jiang <dave.jiang@intel.com> --- v2: - Rename parameter from did_unlock to retry (Jan) fs/xfs/xfs_file.c | 9 ++++----- 1 file changed, 4 insertions(+), 5 deletions(-)