Eric Sandeen
2014-08-21 02:20:21 UTC
xfs_seek_hole & xfs_seek_data are remarkably similar;
so much so that they could be combined, saving a fair
bit of semi-complex code duplication.
The following patch passes generic/285 and generic/286;
is this worth doing, (maybe cleaning up a bit), or
is it too convoluted & confusing?
Signed-off-by: Eric Sandeen <***@redhat.com>
---
xfs_file.c | 174 +++++++++++++++++--------------------------------------------
1 file changed, 50 insertions(+), 124 deletions(-)
diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
index 076b170..321dde6 100644
--- a/fs/xfs/xfs_file.c
+++ b/fs/xfs/xfs_file.c
@@ -964,7 +964,7 @@ xfs_vm_page_mkwrite(
/*
* This type is designed to indicate the type of offset we would like
- * to search from page cache for either xfs_seek_data() or xfs_seek_hole().
+ * to search from page cache for xfs_seek_hole_data().
*/
enum {
HOLE_OFF = 0,
@@ -1021,7 +1021,7 @@ xfs_lookup_buffer_offset(
/*
* This routine is called to find out and return a data or hole offset
* from the page cache for unwritten extents according to the desired
- * type for xfs_seek_data() or xfs_seek_hole().
+ * type for xfs_seek_hole_data().
*
* The argument offset is used to tell where we start to search from the
* page cache. Map is used to figure out the end points of the range to
@@ -1181,9 +1181,10 @@ out:
}
STATIC loff_t
-xfs_seek_data(
+xfs_seek_hole_data(
struct file *file,
- loff_t start)
+ loff_t start,
+ int whence)
{
struct inode *inode = file->f_mapping->host;
struct xfs_inode *ip = XFS_I(inode);
@@ -1195,6 +1196,9 @@ xfs_seek_data(
uint lock;
int error;
+ if (XFS_FORCED_SHUTDOWN(mp))
+ return -EIO;
+
lock = xfs_ilock_data_map_shared(ip);
isize = i_size_read(inode);
@@ -1209,6 +1213,7 @@ xfs_seek_data(
*/
fsbno = XFS_B_TO_FSBT(mp, start);
end = XFS_B_TO_FSB(mp, isize);
+
for (;;) {
struct xfs_bmbt_irec map[2];
int nmap = 2;
@@ -1229,29 +1234,46 @@ xfs_seek_data(
offset = max_t(loff_t, start,
XFS_FSB_TO_B(mp, map[i].br_startoff));
- /* Landed in a data extent */
- if (map[i].br_startblock == DELAYSTARTBLOCK ||
- (map[i].br_state == XFS_EXT_NORM &&
- !isnullstartblock(map[i].br_startblock)))
+ /* Landed in the hole we wanted? */
+ if (whence == SEEK_HOLE &&
+ map[i].br_startblock == HOLESTARTBLOCK)
+ goto out;
+
+ /* Landed in the data extent we wanted? */
+ if (whence == SEEK_DATA &&
+ (map[i].br_startblock == DELAYSTARTBLOCK ||
+ (map[i].br_state == XFS_EXT_NORM &&
+ !isnullstartblock(map[i].br_startblock))))
goto out;
/*
- * Landed in an unwritten extent, try to search data
- * from page cache.
+ * Landed in an unwritten extent, try to search
+ * for hole or data from page cache.
*/
if (map[i].br_state == XFS_EXT_UNWRITTEN) {
if (xfs_find_get_desired_pgoff(inode, &map[i],
- DATA_OFF, &offset))
+ whence == SEEK_HOLE ? HOLE_OFF : DATA_OFF,
+ &offset))
goto out;
}
}
- /*
- * map[0] is hole or its an unwritten extent but
- * without data in page cache. Probably means that
- * we are reading after EOF if nothing in map[1].
- */
if (nmap == 1) {
+ /*
+ * The single map didn't have what we were looking for.
+ * If we were looking for a hole, we are probably
+ * looking past EOF. We should fix offset to point
+ * to the end of the file (i.e., there is an implicit
+ * hole at the end of any file).
+ */
+ if (whence == SEEK_HOLE) {
+ offset = isize;
+ break;
+ }
+ /*
+ * If we were looking for data, it's nowhere to be found
+ */
+ ASSERT(whence == SEEK_DATA);
error = -ENXIO;
goto out_unlock;
}
@@ -1260,125 +1282,30 @@ xfs_seek_data(
/*
* Nothing was found, proceed to the next round of search
- * if reading offset not beyond or hit EOF.
+ * if the next reading offset is not at or beyond EOF.
*/
fsbno = map[i - 1].br_startoff + map[i - 1].br_blockcount;
start = XFS_FSB_TO_B(mp, fsbno);
if (start >= isize) {
+ if (whence == SEEK_HOLE) {
+ offset = isize;
+ break;
+ }
+ ASSERT(whence == SEEK_DATA);
error = -ENXIO;
goto out_unlock;
}
}
out:
- offset = vfs_setpos(file, offset, inode->i_sb->s_maxbytes);
-
-out_unlock:
- xfs_iunlock(ip, lock);
-
- if (error)
- return error;
- return offset;
-}
-
-STATIC loff_t
-xfs_seek_hole(
- struct file *file,
- loff_t start)
-{
- struct inode *inode = file->f_mapping->host;
- struct xfs_inode *ip = XFS_I(inode);
- struct xfs_mount *mp = ip->i_mount;
- loff_t uninitialized_var(offset);
- xfs_fsize_t isize;
- xfs_fileoff_t fsbno;
- xfs_filblks_t end;
- uint lock;
- int error;
-
- if (XFS_FORCED_SHUTDOWN(mp))
- return -EIO;
-
- lock = xfs_ilock_data_map_shared(ip);
-
- isize = i_size_read(inode);
- if (start >= isize) {
- error = -ENXIO;
- goto out_unlock;
- }
-
- fsbno = XFS_B_TO_FSBT(mp, start);
- end = XFS_B_TO_FSB(mp, isize);
-
- for (;;) {
- struct xfs_bmbt_irec map[2];
- int nmap = 2;
- unsigned int i;
-
- error = xfs_bmapi_read(ip, fsbno, end - fsbno, map, &nmap,
- XFS_BMAPI_ENTIRE);
- if (error)
- goto out_unlock;
-
- /* No extents at given offset, must be beyond EOF */
- if (nmap == 0) {
- error = -ENXIO;
- goto out_unlock;
- }
-
- for (i = 0; i < nmap; i++) {
- offset = max_t(loff_t, start,
- XFS_FSB_TO_B(mp, map[i].br_startoff));
-
- /* Landed in a hole */
- if (map[i].br_startblock == HOLESTARTBLOCK)
- goto out;
-
- /*
- * Landed in an unwritten extent, try to search hole
- * from page cache.
- */
- if (map[i].br_state == XFS_EXT_UNWRITTEN) {
- if (xfs_find_get_desired_pgoff(inode, &map[i],
- HOLE_OFF, &offset))
- goto out;
- }
- }
-
- /*
- * map[0] contains data or its unwritten but contains
- * data in page cache, probably means that we are
- * reading after EOF. We should fix offset to point
- * to the end of the file(i.e., there is an implicit
- * hole at the end of any file).
- */
- if (nmap == 1) {
- offset = isize;
- break;
- }
-
- ASSERT(i > 1);
-
- /*
- * Both mappings contains data, proceed to the next round of
- * search if the current reading offset not beyond or hit EOF.
- */
- fsbno = map[i - 1].br_startoff + map[i - 1].br_blockcount;
- start = XFS_FSB_TO_B(mp, fsbno);
- if (start >= isize) {
- offset = isize;
- break;
- }
- }
-
-out:
/*
- * At this point, we must have found a hole. However, the returned
+ * If at this point we have found the hole we wanted, the returned
* offset may be bigger than the file size as it may be aligned to
- * page boundary for unwritten extents, we need to deal with this
+ * page boundary for unwritten extents. We need to deal with this
* situation in particular.
*/
- offset = min_t(loff_t, offset, isize);
+ if (whence == SEEK_HOLE)
+ offset = min_t(loff_t, offset, isize);
offset = vfs_setpos(file, offset, inode->i_sb->s_maxbytes);
out_unlock:
@@ -1400,10 +1327,9 @@ xfs_file_llseek(
case SEEK_CUR:
case SEEK_SET:
return generic_file_llseek(file, offset, origin);
- case SEEK_DATA:
- return xfs_seek_data(file, offset);
case SEEK_HOLE:
- return xfs_seek_hole(file, offset);
+ case SEEK_DATA:
+ return xfs_seek_hole_data(file, offset, origin);
default:
return -EINVAL;
}
so much so that they could be combined, saving a fair
bit of semi-complex code duplication.
The following patch passes generic/285 and generic/286;
is this worth doing, (maybe cleaning up a bit), or
is it too convoluted & confusing?
Signed-off-by: Eric Sandeen <***@redhat.com>
---
xfs_file.c | 174 +++++++++++++++++--------------------------------------------
1 file changed, 50 insertions(+), 124 deletions(-)
diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
index 076b170..321dde6 100644
--- a/fs/xfs/xfs_file.c
+++ b/fs/xfs/xfs_file.c
@@ -964,7 +964,7 @@ xfs_vm_page_mkwrite(
/*
* This type is designed to indicate the type of offset we would like
- * to search from page cache for either xfs_seek_data() or xfs_seek_hole().
+ * to search from page cache for xfs_seek_hole_data().
*/
enum {
HOLE_OFF = 0,
@@ -1021,7 +1021,7 @@ xfs_lookup_buffer_offset(
/*
* This routine is called to find out and return a data or hole offset
* from the page cache for unwritten extents according to the desired
- * type for xfs_seek_data() or xfs_seek_hole().
+ * type for xfs_seek_hole_data().
*
* The argument offset is used to tell where we start to search from the
* page cache. Map is used to figure out the end points of the range to
@@ -1181,9 +1181,10 @@ out:
}
STATIC loff_t
-xfs_seek_data(
+xfs_seek_hole_data(
struct file *file,
- loff_t start)
+ loff_t start,
+ int whence)
{
struct inode *inode = file->f_mapping->host;
struct xfs_inode *ip = XFS_I(inode);
@@ -1195,6 +1196,9 @@ xfs_seek_data(
uint lock;
int error;
+ if (XFS_FORCED_SHUTDOWN(mp))
+ return -EIO;
+
lock = xfs_ilock_data_map_shared(ip);
isize = i_size_read(inode);
@@ -1209,6 +1213,7 @@ xfs_seek_data(
*/
fsbno = XFS_B_TO_FSBT(mp, start);
end = XFS_B_TO_FSB(mp, isize);
+
for (;;) {
struct xfs_bmbt_irec map[2];
int nmap = 2;
@@ -1229,29 +1234,46 @@ xfs_seek_data(
offset = max_t(loff_t, start,
XFS_FSB_TO_B(mp, map[i].br_startoff));
- /* Landed in a data extent */
- if (map[i].br_startblock == DELAYSTARTBLOCK ||
- (map[i].br_state == XFS_EXT_NORM &&
- !isnullstartblock(map[i].br_startblock)))
+ /* Landed in the hole we wanted? */
+ if (whence == SEEK_HOLE &&
+ map[i].br_startblock == HOLESTARTBLOCK)
+ goto out;
+
+ /* Landed in the data extent we wanted? */
+ if (whence == SEEK_DATA &&
+ (map[i].br_startblock == DELAYSTARTBLOCK ||
+ (map[i].br_state == XFS_EXT_NORM &&
+ !isnullstartblock(map[i].br_startblock))))
goto out;
/*
- * Landed in an unwritten extent, try to search data
- * from page cache.
+ * Landed in an unwritten extent, try to search
+ * for hole or data from page cache.
*/
if (map[i].br_state == XFS_EXT_UNWRITTEN) {
if (xfs_find_get_desired_pgoff(inode, &map[i],
- DATA_OFF, &offset))
+ whence == SEEK_HOLE ? HOLE_OFF : DATA_OFF,
+ &offset))
goto out;
}
}
- /*
- * map[0] is hole or its an unwritten extent but
- * without data in page cache. Probably means that
- * we are reading after EOF if nothing in map[1].
- */
if (nmap == 1) {
+ /*
+ * The single map didn't have what we were looking for.
+ * If we were looking for a hole, we are probably
+ * looking past EOF. We should fix offset to point
+ * to the end of the file (i.e., there is an implicit
+ * hole at the end of any file).
+ */
+ if (whence == SEEK_HOLE) {
+ offset = isize;
+ break;
+ }
+ /*
+ * If we were looking for data, it's nowhere to be found
+ */
+ ASSERT(whence == SEEK_DATA);
error = -ENXIO;
goto out_unlock;
}
@@ -1260,125 +1282,30 @@ xfs_seek_data(
/*
* Nothing was found, proceed to the next round of search
- * if reading offset not beyond or hit EOF.
+ * if the next reading offset is not at or beyond EOF.
*/
fsbno = map[i - 1].br_startoff + map[i - 1].br_blockcount;
start = XFS_FSB_TO_B(mp, fsbno);
if (start >= isize) {
+ if (whence == SEEK_HOLE) {
+ offset = isize;
+ break;
+ }
+ ASSERT(whence == SEEK_DATA);
error = -ENXIO;
goto out_unlock;
}
}
out:
- offset = vfs_setpos(file, offset, inode->i_sb->s_maxbytes);
-
-out_unlock:
- xfs_iunlock(ip, lock);
-
- if (error)
- return error;
- return offset;
-}
-
-STATIC loff_t
-xfs_seek_hole(
- struct file *file,
- loff_t start)
-{
- struct inode *inode = file->f_mapping->host;
- struct xfs_inode *ip = XFS_I(inode);
- struct xfs_mount *mp = ip->i_mount;
- loff_t uninitialized_var(offset);
- xfs_fsize_t isize;
- xfs_fileoff_t fsbno;
- xfs_filblks_t end;
- uint lock;
- int error;
-
- if (XFS_FORCED_SHUTDOWN(mp))
- return -EIO;
-
- lock = xfs_ilock_data_map_shared(ip);
-
- isize = i_size_read(inode);
- if (start >= isize) {
- error = -ENXIO;
- goto out_unlock;
- }
-
- fsbno = XFS_B_TO_FSBT(mp, start);
- end = XFS_B_TO_FSB(mp, isize);
-
- for (;;) {
- struct xfs_bmbt_irec map[2];
- int nmap = 2;
- unsigned int i;
-
- error = xfs_bmapi_read(ip, fsbno, end - fsbno, map, &nmap,
- XFS_BMAPI_ENTIRE);
- if (error)
- goto out_unlock;
-
- /* No extents at given offset, must be beyond EOF */
- if (nmap == 0) {
- error = -ENXIO;
- goto out_unlock;
- }
-
- for (i = 0; i < nmap; i++) {
- offset = max_t(loff_t, start,
- XFS_FSB_TO_B(mp, map[i].br_startoff));
-
- /* Landed in a hole */
- if (map[i].br_startblock == HOLESTARTBLOCK)
- goto out;
-
- /*
- * Landed in an unwritten extent, try to search hole
- * from page cache.
- */
- if (map[i].br_state == XFS_EXT_UNWRITTEN) {
- if (xfs_find_get_desired_pgoff(inode, &map[i],
- HOLE_OFF, &offset))
- goto out;
- }
- }
-
- /*
- * map[0] contains data or its unwritten but contains
- * data in page cache, probably means that we are
- * reading after EOF. We should fix offset to point
- * to the end of the file(i.e., there is an implicit
- * hole at the end of any file).
- */
- if (nmap == 1) {
- offset = isize;
- break;
- }
-
- ASSERT(i > 1);
-
- /*
- * Both mappings contains data, proceed to the next round of
- * search if the current reading offset not beyond or hit EOF.
- */
- fsbno = map[i - 1].br_startoff + map[i - 1].br_blockcount;
- start = XFS_FSB_TO_B(mp, fsbno);
- if (start >= isize) {
- offset = isize;
- break;
- }
- }
-
-out:
/*
- * At this point, we must have found a hole. However, the returned
+ * If at this point we have found the hole we wanted, the returned
* offset may be bigger than the file size as it may be aligned to
- * page boundary for unwritten extents, we need to deal with this
+ * page boundary for unwritten extents. We need to deal with this
* situation in particular.
*/
- offset = min_t(loff_t, offset, isize);
+ if (whence == SEEK_HOLE)
+ offset = min_t(loff_t, offset, isize);
offset = vfs_setpos(file, offset, inode->i_sb->s_maxbytes);
out_unlock:
@@ -1400,10 +1327,9 @@ xfs_file_llseek(
case SEEK_CUR:
case SEEK_SET:
return generic_file_llseek(file, offset, origin);
- case SEEK_DATA:
- return xfs_seek_data(file, offset);
case SEEK_HOLE:
- return xfs_seek_hole(file, offset);
+ case SEEK_DATA:
+ return xfs_seek_hole_data(file, offset, origin);
default:
return -EINVAL;
}