From 49c69591c80648c14ff87525e97ee6ebe3a343cb Mon Sep 17 00:00:00 2001 From: Eric Sandeen Date: Tue, 9 Sep 2014 11:56:48 +1000 Subject: [PATCH] xfs: combine xfs_seek_hole & xfs_seek_data xfs_seek_hole & xfs_seek_data are remarkably similar; so much so that they can be combined, saving a fair bit of semi-complex code duplication. The following patch passes generic/285 and generic/286, which specifically test seek behavior. Signed-off-by: Eric Sandeen Reviewed-by: Brian Foster Reviewed-by: Jie Liu Signed-off-by: Dave Chinner --- fs/xfs/xfs_file.c | 172 ++++++++++++++-------------------------------- 1 file changed, 50 insertions(+), 122 deletions(-) diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c index 076b1708d134..1da3b7db5bf7 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 @@ xfs_find_get_desired_pgoff( } 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 +1234,48 @@ 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]. + * We only received one extent out of the two requested. This + * means we've hit EOF and didn't find what we are looking for. */ if (nmap == 1) { + /* + * If we were looking for a hole, set offset 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 +1284,30 @@ 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 +1329,9 @@ 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; } -- GitLab