| Message ID | 150846719726.24336.3564801642993121646.stgit@dwillia2-desk3.amr.corp.intel.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Thu, 2017-10-19 at 19:39 -0700, Dan Williams wrote: > Commit 128a37852234 "fs: fix data races on inode->i_flctx" converted > checks of inode->i_flctx to use smp_load_acquire(), but it did not > convert break_layout(). smp_load_acquire() includes a READ_ONCE(). There > should be no functional difference since __break_lease repeats the > sequence, but this is a clean up to unify all ->i_flctx lookups on a > common pattern. > > Cc: Christoph Hellwig <hch@lst.de> > Cc: Alexander Viro <viro@zeniv.linux.org.uk> > Cc: Ross Zwisler <ross.zwisler@linux.intel.com> > Cc: Jeff Layton <jlayton@poochiereds.net> > Cc: "J. Bruce Fields" <bfields@fieldses.org> > Signed-off-by: Dan Williams <dan.j.williams@intel.com> > --- > include/linux/fs.h | 10 ++++++---- > 1 file changed, 6 insertions(+), 4 deletions(-) > > diff --git a/include/linux/fs.h b/include/linux/fs.h > index 13dab191a23e..eace2c5396a7 100644 > --- a/include/linux/fs.h > +++ b/include/linux/fs.h > @@ -2281,8 +2281,9 @@ static inline int break_lease(struct inode *inode, unsigned int mode) > * could end up racing with tasks trying to set a new lease on this > * file. > */ > - smp_mb(); > - if (inode->i_flctx && !list_empty_careful(&inode->i_flctx->flc_lease)) > + struct file_lock_context *ctx = smp_load_acquire(&inode->i_flctx); > + > + if (ctx && !list_empty_careful(&ctx->flc_lease)) > return __break_lease(inode, mode, FL_LEASE); > return 0; > } > @@ -2325,8 +2326,9 @@ static inline int break_deleg_wait(struct inode **delegated_inode) > > static inline int break_layout(struct inode *inode, bool wait) > { > - smp_mb(); > - if (inode->i_flctx && !list_empty_careful(&inode->i_flctx->flc_lease)) > + struct file_lock_context *ctx = smp_load_acquire(&inode->i_flctx); > + > + if (ctx && !list_empty_careful(&ctx->flc_lease)) > return __break_lease(inode, > wait ? O_WRONLY : O_WRONLY | O_NONBLOCK, > FL_LAYOUT); > Nice catch. This can go in independently of the rest of the patches in the series, I think. I'll assume Andrew is picking this up since he's in the "To:", but let me know if you need me to get it. Reviewed-by: Jeff Layton <jlayton@kernel.org>
diff --git a/include/linux/fs.h b/include/linux/fs.h index 13dab191a23e..eace2c5396a7 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -2281,8 +2281,9 @@ static inline int break_lease(struct inode *inode, unsigned int mode) * could end up racing with tasks trying to set a new lease on this * file. */ - smp_mb(); - if (inode->i_flctx && !list_empty_careful(&inode->i_flctx->flc_lease)) + struct file_lock_context *ctx = smp_load_acquire(&inode->i_flctx); + + if (ctx && !list_empty_careful(&ctx->flc_lease)) return __break_lease(inode, mode, FL_LEASE); return 0; } @@ -2325,8 +2326,9 @@ static inline int break_deleg_wait(struct inode **delegated_inode) static inline int break_layout(struct inode *inode, bool wait) { - smp_mb(); - if (inode->i_flctx && !list_empty_careful(&inode->i_flctx->flc_lease)) + struct file_lock_context *ctx = smp_load_acquire(&inode->i_flctx); + + if (ctx && !list_empty_careful(&ctx->flc_lease)) return __break_lease(inode, wait ? O_WRONLY : O_WRONLY | O_NONBLOCK, FL_LAYOUT);
Commit 128a37852234 "fs: fix data races on inode->i_flctx" converted checks of inode->i_flctx to use smp_load_acquire(), but it did not convert break_layout(). smp_load_acquire() includes a READ_ONCE(). There should be no functional difference since __break_lease repeats the sequence, but this is a clean up to unify all ->i_flctx lookups on a common pattern. Cc: Christoph Hellwig <hch@lst.de> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Ross Zwisler <ross.zwisler@linux.intel.com> Cc: Jeff Layton <jlayton@poochiereds.net> Cc: "J. Bruce Fields" <bfields@fieldses.org> Signed-off-by: Dan Williams <dan.j.williams@intel.com> --- include/linux/fs.h | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-)