| Message ID | 3e83a70c4442c6aeb15b7913c39f853e7386a3c3.1565609891.git.mbobrowski@mbobrowski.org |
|---|---|
| State | Superseded |
| Headers | show |
| Series | ext4: direct IO via iomap infrastructure | expand |
On Mon, Aug 12, 2019 at 10:52:35PM +1000, Matthew Bobrowski wrote: > +#ifdef CONFIG_FS_ENCRYPTION > + if (IS_ENCRYPTED(inode)) > + return false; > +#endif This could use IS_ENABLED. > return -EIO; > > if (!iov_iter_count(to)) > return 0; /* skip atime */ > > #ifdef CONFIG_FS_DAX > - if (IS_DAX(file_inode(iocb->ki_filp))) > + if (IS_DAX(inode)) > return ext4_dax_read_iter(iocb, to); > #endif Same here.
On Mon, Aug 12, 2019 at 10:18:35AM -0700, Christoph Hellwig wrote: > > return -EIO; > > > > if (!iov_iter_count(to)) > > return 0; /* skip atime */ > > > > #ifdef CONFIG_FS_DAX > > - if (IS_DAX(file_inode(iocb->ki_filp))) > > + if (IS_DAX(inode)) > > return ext4_dax_read_iter(iocb, to); > > #endif > > Same here. It doesn't even need IS_ENABLED. include/linux/fs.h:#define IS_DAX(inode) ((inode)->i_flags & S_DAX) #ifdef CONFIG_FS_DAX #define S_DAX 8192 /* Direct Access, avoiding the page cache */ #else #define S_DAX 0 /* Make all the DAX code disappear */ #endif
On Mon, Aug 12, 2019 at 01:17:35PM -0700, Matthew Wilcox wrote: > On Mon, Aug 12, 2019 at 10:18:35AM -0700, Christoph Hellwig wrote: > > > return -EIO; > > > > > > if (!iov_iter_count(to)) > > > return 0; /* skip atime */ > > > > > > #ifdef CONFIG_FS_DAX > > > - if (IS_DAX(file_inode(iocb->ki_filp))) > > > + if (IS_DAX(inode)) > > > return ext4_dax_read_iter(iocb, to); > > > #endif > > > > Same here. > > It doesn't even need IS_ENABLED. > > include/linux/fs.h:#define IS_DAX(inode) ((inode)->i_flags & S_DAX) > > #ifdef CONFIG_FS_DAX > #define S_DAX 8192 /* Direct Access, avoiding the page cache */ > #else > #define S_DAX 0 /* Make all the DAX code disappear */ > #endif Ah, clever - I like it! I actually didn't see this and thank you for highlighting. I guess I will be dropping the CONFIG_FS_DAX statement here... --M
diff --git a/fs/ext4/file.c b/fs/ext4/file.c index 70b0438dbc94..360eff7b6aa2 100644 --- a/fs/ext4/file.c +++ b/fs/ext4/file.c @@ -34,6 +34,53 @@ #include "xattr.h" #include "acl.h" +static bool ext4_dio_checks(struct inode *inode) +{ +#ifdef CONFIG_FS_ENCRYPTION + if (IS_ENCRYPTED(inode)) + return false; +#endif + if (ext4_should_journal_data(inode)) + return false; + if (ext4_has_inline_data(inode)) + return false; + return true; +} + +static ssize_t ext4_dio_read_iter(struct kiocb *iocb, struct iov_iter *to) +{ + ssize_t ret; + struct inode *inode = file_inode(iocb->ki_filp); + + /* + * Get exclusion from truncate and other inode operations. + */ + if (!inode_trylock_shared(inode)) { + if (iocb->ki_flags & IOCB_NOWAIT) + return -EAGAIN; + inode_lock_shared(inode); + } + + if (!ext4_dio_checks(inode)) { + inode_unlock_shared(inode); + /* + * Fallback to buffered IO if the operation being + * performed on the inode is not supported by direct + * IO. The IOCB_DIRECT flag from iocb->ki_flags needs + * to be cleared here to ensure that the direct IO + * code path in generic_file_read_iter() is not taken. + */ + iocb->ki_flags &= ~IOCB_DIRECT; + return generic_file_read_iter(iocb, to); + } + + ret = iomap_dio_rw(iocb, to, &ext4_iomap_ops, NULL); + inode_unlock_shared(inode); + + file_accessed(iocb->ki_filp); + return ret; +} + #ifdef CONFIG_FS_DAX static ssize_t ext4_dax_read_iter(struct kiocb *iocb, struct iov_iter *to) { @@ -64,16 +111,20 @@ static ssize_t ext4_dax_read_iter(struct kiocb *iocb, struct iov_iter *to) static ssize_t ext4_file_read_iter(struct kiocb *iocb, struct iov_iter *to) { - if (unlikely(ext4_forced_shutdown(EXT4_SB(file_inode(iocb->ki_filp)->i_sb)))) + struct inode *inode = file_inode(iocb->ki_filp); + + if (unlikely(ext4_forced_shutdown(EXT4_SB(inode->i_sb)))) return -EIO; if (!iov_iter_count(to)) return 0; /* skip atime */ #ifdef CONFIG_FS_DAX - if (IS_DAX(file_inode(iocb->ki_filp))) + if (IS_DAX(inode)) return ext4_dax_read_iter(iocb, to); #endif + if (iocb->ki_flags & IOCB_DIRECT) + return ext4_dio_read_iter(iocb, to); return generic_file_read_iter(iocb, to); }
This patch introduces a new direct IO read code path implementation that makes use of the iomap infrastructure. The new function ext4_dio_read_iter() is responsible for calling into the iomap infrastructure via iomap_dio_rw(). If the inode in question does not pass preliminary checks in ext4_dio_checks(), then we simply fallback to buffered IO and try to take that path. Prior to doing so, we drop the IOCB_DIRECT flag from iocb->ki_flags to prevent generic_file_read_iter() from taking the direct IO code path once again. Signed-off-by: Matthew Bobrowski <mbobrowski@mbobrowski.org> --- fs/ext4/file.c | 55 +++++++++++++++++++++++++++++++++++++++++++++++++++++-- 1 file changed, 53 insertions(+), 2 deletions(-)