Message ID | 1497624680-16685-5-git-send-email-agruenba@redhat.com (mailing list archive) |
---|---|
State | New, archived |
Headers | show |
On Fri, Jun 16, 2017 at 04:51:17PM +0200, Andreas Gruenbacher wrote: > Filesystems can use this for implementing lseek SEEK_HOLE / SEEK_DATA > support via iomap. > > The __iomap_seek_hole_data helper takes an additional size argument and > doesn't reposition the file offset; this is for internal use for xfs > quota files which don't maintain the inode size. > > Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com> > --- > fs/iomap.c | 81 +++++++++++++++++++++++++++++++++++++++++++++++++++ > include/linux/iomap.h | 6 ++++ > 2 files changed, 87 insertions(+) > > diff --git a/fs/iomap.c b/fs/iomap.c > index 4b10892..cf01694 100644 > --- a/fs/iomap.c > +++ b/fs/iomap.c > @@ -584,6 +584,87 @@ int iomap_fiemap(struct inode *inode, struct fiemap_extent_info *fi, > } > EXPORT_SYMBOL_GPL(iomap_fiemap); > > +static loff_t > +iomap_seek_hole_actor(struct inode *inode, loff_t offset, loff_t length, > + void *data, struct iomap *iomap) > +{ > + if (iomap->type == IOMAP_HOLE) Echoing Dave's comments further on (sorry, I tend to read the patchset but reply in reverse order, distractions notwithstanding), for SEEK_{HOLE,DATA} you'd want to test for type == IOMAP_HOLE || type == IOMAP_UNWRITTEN since unwritten (i.e. fallocated) areas are treated as holes. --D > + return 0; > + return iomap->offset + iomap->length - offset; > +} > + > +static loff_t > +iomap_seek_data_actor(struct inode *inode, loff_t offset, loff_t length, > + void *data, struct iomap *iomap) > +{ > + if (iomap->type != IOMAP_HOLE) > + return 0; > + return iomap->offset + iomap->length - offset; > +} > + > +loff_t > +__iomap_seek_hole_data(struct inode *inode, loff_t offset, loff_t size, > + int whence, const struct iomap_ops *ops) > +{ > + static loff_t (*actor)(struct inode *, loff_t, loff_t, void *, > + struct iomap *); > + loff_t len = size - offset; > + loff_t ret; > + > + /* Nothing to be found beyond the end of the file. */ > + if (len <= 0) > + return -ENXIO; > + > + switch(whence) { > + case SEEK_HOLE: > + actor = iomap_seek_hole_actor; > + break; > + > + case SEEK_DATA: > + actor = iomap_seek_data_actor; > + break; > + } > + > + while (len > 0) { > + ret = iomap_apply(inode, offset, len, IOMAP_REPORT, ops, > + NULL, actor); > + if (ret <= 0) { > + if (ret < 0) > + return ret; > + break; > + } > + offset += ret; > + len -= ret; > + } > + > + if (len <= 0) { > + /* There is an implicit hole at the end of the file. */ > + if (whence != SEEK_HOLE) > + offset = -ENXIO; > + > + /* The last segment can extend beyond the end of the file. */ > + if (offset > size) > + offset = size; > + } > + > + return offset; > +} > +EXPORT_SYMBOL_GPL(__iomap_seek_hole_data); > + > +loff_t > +iomap_seek_hole_data(struct file *file, loff_t offset, int whence, > + const struct iomap_ops *ops) > +{ > + struct inode *inode = file->f_mapping->host; > + > + offset = __iomap_seek_hole_data(inode, offset, i_size_read(inode), > + whence, ops); > + if (offset <= 0) > + return offset; > + return vfs_setpos(file, offset, inode->i_sb->s_maxbytes); > +} > +EXPORT_SYMBOL_GPL(iomap_seek_hole_data); > + > /* > * Private flags for iomap_dio, must not overlap with the public ones in > * iomap.h: > diff --git a/include/linux/iomap.h b/include/linux/iomap.h > index 9d64933..49b6ec0 100644 > --- a/include/linux/iomap.h > +++ b/include/linux/iomap.h > @@ -85,6 +85,12 @@ int iomap_page_mkwrite(struct vm_fault *vmf, const struct iomap_ops *ops); > int iomap_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo, > loff_t start, loff_t len, const struct iomap_ops *ops); > > +struct file; > +loff_t __iomap_seek_hole_data(struct inode *inode, loff_t pos, loff_t size, > + int whence, const struct iomap_ops *ops); > +loff_t iomap_seek_hole_data(struct file *file, loff_t pos, > + int whence, const struct iomap_ops *ops); > + > /* > * Flags for direct I/O ->end_io: > */ > -- > 2.7.5 >
diff --git a/fs/iomap.c b/fs/iomap.c index 4b10892..cf01694 100644 --- a/fs/iomap.c +++ b/fs/iomap.c @@ -584,6 +584,87 @@ int iomap_fiemap(struct inode *inode, struct fiemap_extent_info *fi, } EXPORT_SYMBOL_GPL(iomap_fiemap); +static loff_t +iomap_seek_hole_actor(struct inode *inode, loff_t offset, loff_t length, + void *data, struct iomap *iomap) +{ + if (iomap->type == IOMAP_HOLE) + return 0; + return iomap->offset + iomap->length - offset; +} + +static loff_t +iomap_seek_data_actor(struct inode *inode, loff_t offset, loff_t length, + void *data, struct iomap *iomap) +{ + if (iomap->type != IOMAP_HOLE) + return 0; + return iomap->offset + iomap->length - offset; +} + +loff_t +__iomap_seek_hole_data(struct inode *inode, loff_t offset, loff_t size, + int whence, const struct iomap_ops *ops) +{ + static loff_t (*actor)(struct inode *, loff_t, loff_t, void *, + struct iomap *); + loff_t len = size - offset; + loff_t ret; + + /* Nothing to be found beyond the end of the file. */ + if (len <= 0) + return -ENXIO; + + switch(whence) { + case SEEK_HOLE: + actor = iomap_seek_hole_actor; + break; + + case SEEK_DATA: + actor = iomap_seek_data_actor; + break; + } + + while (len > 0) { + ret = iomap_apply(inode, offset, len, IOMAP_REPORT, ops, + NULL, actor); + if (ret <= 0) { + if (ret < 0) + return ret; + break; + } + offset += ret; + len -= ret; + } + + if (len <= 0) { + /* There is an implicit hole at the end of the file. */ + if (whence != SEEK_HOLE) + offset = -ENXIO; + + /* The last segment can extend beyond the end of the file. */ + if (offset > size) + offset = size; + } + + return offset; +} +EXPORT_SYMBOL_GPL(__iomap_seek_hole_data); + +loff_t +iomap_seek_hole_data(struct file *file, loff_t offset, int whence, + const struct iomap_ops *ops) +{ + struct inode *inode = file->f_mapping->host; + + offset = __iomap_seek_hole_data(inode, offset, i_size_read(inode), + whence, ops); + if (offset <= 0) + return offset; + return vfs_setpos(file, offset, inode->i_sb->s_maxbytes); +} +EXPORT_SYMBOL_GPL(iomap_seek_hole_data); + /* * Private flags for iomap_dio, must not overlap with the public ones in * iomap.h: diff --git a/include/linux/iomap.h b/include/linux/iomap.h index 9d64933..49b6ec0 100644 --- a/include/linux/iomap.h +++ b/include/linux/iomap.h @@ -85,6 +85,12 @@ int iomap_page_mkwrite(struct vm_fault *vmf, const struct iomap_ops *ops); int iomap_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo, loff_t start, loff_t len, const struct iomap_ops *ops); +struct file; +loff_t __iomap_seek_hole_data(struct inode *inode, loff_t pos, loff_t size, + int whence, const struct iomap_ops *ops); +loff_t iomap_seek_hole_data(struct file *file, loff_t pos, + int whence, const struct iomap_ops *ops); + /* * Flags for direct I/O ->end_io: */
Filesystems can use this for implementing lseek SEEK_HOLE / SEEK_DATA support via iomap. The __iomap_seek_hole_data helper takes an additional size argument and doesn't reposition the file offset; this is for internal use for xfs quota files which don't maintain the inode size. Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com> --- fs/iomap.c | 81 +++++++++++++++++++++++++++++++++++++++++++++++++++ include/linux/iomap.h | 6 ++++ 2 files changed, 87 insertions(+)