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Message-Id: <1359085145-15490-2-git-send-email-wenqing.lz@taobao.com> Date: Fri, 25 Jan 2013 11:39:04 +0800 From: Zheng Liu <gnehzuil.liu@...il.com> To: linux-ext4@...r.kernel.org Cc: "Theodore Ts'o" <tytso@....edu>, Zheng Liu <wenqing.lz@...bao.com> Subject: [PATCH 1/2 v4] libext2fs: introduce lseek SEEK_DATA/HOLE From: Zheng Liu <wenqing.lz@...bao.com> ext2fs_file_llseek is extented to introduce SEEK_DATA/HOLE. In *_data() function it will find the next data, and in *_hole() function it will find the next hole. A new error code called EXT2_ET_SEEK_BEYOND_EOF is define to indicate that the offset is beyond the end of file. Cc: "Theodore Ts'o" <tytso@....edu> Signed-off-by: Zheng Liu <wenqing.lz@...bao.com> --- lib/ext2fs/ext2_err.et.in | 3 + lib/ext2fs/ext2fs.h | 2 + lib/ext2fs/fileio.c | 197 +++++++++++++++++++++++++++++++++++++++++++++- 3 files changed, 201 insertions(+), 1 deletion(-) diff --git a/lib/ext2fs/ext2_err.et.in b/lib/ext2fs/ext2_err.et.in index d20c6b7..6e79b97 100644 --- a/lib/ext2fs/ext2_err.et.in +++ b/lib/ext2fs/ext2_err.et.in @@ -476,4 +476,7 @@ ec EXT2_ET_MMP_CSUM_INVALID, ec EXT2_ET_FILE_EXISTS, "Ext2 file already exists" +ec EXT2_ET_SEEK_BEYOND_EOF, + "lseek beyond the EOF" + end diff --git a/lib/ext2fs/ext2fs.h b/lib/ext2fs/ext2fs.h index 7139b4d..ce7c38a 100644 --- a/lib/ext2fs/ext2fs.h +++ b/lib/ext2fs/ext2fs.h @@ -160,6 +160,8 @@ typedef struct ext2_file *ext2_file_t; #define EXT2_SEEK_SET 0 #define EXT2_SEEK_CUR 1 #define EXT2_SEEK_END 2 +#define EXT2_SEEK_DATA 3 +#define EXT2_SEEK_HOLE 4 /* * Flags for the ext2_filsys structure and for ext2fs_open() diff --git a/lib/ext2fs/fileio.c b/lib/ext2fs/fileio.c index 1f7002c..6cb2e43 100644 --- a/lib/ext2fs/fileio.c +++ b/lib/ext2fs/fileio.c @@ -312,10 +312,201 @@ fail: return retval; } +static errcode_t ext2fs_file_llseek_data_ext(ext2_file_t file, __u64 offset) +{ + ext2_extent_handle_t handle = 0; + struct ext2fs_extent extent; + ext2_filsys fs = file->fs; + errcode_t retval = 0; + unsigned int dataoff; + + retval = ext2fs_extent_open2(fs, file->ino, &file->inode, &handle); + if (retval) + return retval; + + while (file->blockno * fs->blocksize < EXT2_I_SIZE(&file->inode)) { + retval = ext2fs_extent_goto(handle, file->blockno); + if (retval && retval != EXT2_ET_EXTENT_NOT_FOUND) + goto done; + if (retval == EXT2_ET_EXTENT_NOT_FOUND) { + file->blockno++; + } else { + retval = ext2fs_extent_get(handle, EXT2_EXTENT_CURRENT, + &extent); + if (retval) + goto done; + /* + * Here we skip uninit block because uninit block is + * as a hole. + */ + if (extent.e_flags & EXT2_EXTENT_FLAGS_UNINIT) { + file->blockno++; + continue; + } + dataoff = file->blockno - extent.e_lblk; + if (file->blockno >= extent.e_lblk && + dataoff <= extent.e_len) { + if (file->blockno == offset / fs->blocksize) + file->pos = offset; + else + file->pos = file->blockno * + fs->blocksize; + break; + } + } + } + +done: + ext2fs_extent_free(handle); + return retval; +} + +static errcode_t ext2fs_file_llseek_data_ind(ext2_file_t file, __u64 offset) +{ + ext2_filsys fs = file->fs; + errcode_t retval = 0; + + while (file->blockno * fs->blocksize < EXT2_I_SIZE(&file->inode)) { + retval = ext2fs_bmap2(fs, file->ino, &file->inode, BMAP_BUFFER, + 0, file->blockno, 0, &file->physblock); + if (retval) + return retval; + /* + * Here we don't care about uninit block because indirect-based + * file doesn't support it. + */ + if (file->physblock == 0) { + file->blockno++; + } else { + if (file->blockno == offset / fs->blocksize) + file->pos = offset; + else + file->pos = file->blockno * fs->blocksize; + break; + } + } + + return retval; +} + +static errcode_t ext2fs_file_llseek_data(ext2_file_t file, __u64 offset) +{ + ext2_filsys fs = file->fs; + errcode_t retval; + + file->blockno = offset / fs->blocksize; + + if (file->inode.i_flags & EXT4_EXTENTS_FL) + retval = ext2fs_file_llseek_data_ext(file, offset); + else + retval = ext2fs_file_llseek_data_ind(file, offset); + + /* notify the caller that there is no any data */ + if (file->blockno * fs->blocksize >= EXT2_I_SIZE(&file->inode)) + return EXT2_ET_SEEK_BEYOND_EOF; + + return retval; +} + +static errcode_t ext2fs_file_llseek_hole_ext(ext2_file_t file, __u64 offset) +{ + ext2_extent_handle_t handle = 0; + struct ext2fs_extent extent; + ext2_filsys fs = file->fs; + errcode_t retval = 0; + unsigned int dataoff; + + retval = ext2fs_extent_open2(fs, file->ino, &file->inode, &handle); + if (retval) + return retval; + + while (file->blockno * fs->blocksize < EXT2_I_SIZE(&file->inode)) { + retval = ext2fs_extent_goto(handle, file->blockno); + if (retval && retval != EXT2_ET_EXTENT_NOT_FOUND) + goto done; + if (retval == EXT2_ET_EXTENT_NOT_FOUND) { + if (file->blockno == offset / fs->blocksize) + file->pos = offset; + else + file->pos = file->blockno * fs->blocksize; + break; + } else { + retval = ext2fs_extent_get(handle, EXT2_EXTENT_CURRENT, + &extent); + if (retval) + goto done; + /* Here uninit block is as a hole */ + if (extent.e_flags & EXT2_EXTENT_FLAGS_UNINIT) { + if (file->blockno == offset / fs->blocksize) + file->pos = offset; + else + file->pos = file->blockno * + fs->blocksize; + break; + } + dataoff = file->blockno - extent.e_lblk; + if (file->blockno >= extent.e_lblk && + dataoff <= extent.e_len) + file->blockno = extent.e_lblk + extent.e_len; + } + } + +done: + ext2fs_extent_free(handle); + return retval; +} + +static errcode_t ext2fs_file_llseek_hole_ind(ext2_file_t file, __u64 offset) +{ + ext2_filsys fs = file->fs; + errcode_t retval = 0; + + while (file->blockno * fs->blocksize < EXT2_I_SIZE(&file->inode)) { + retval = ext2fs_bmap2(fs, file->ino, &file->inode, BMAP_BUFFER, + 0, file->blockno, 0, &file->physblock); + if (retval) + return retval; + /* + * Here we don't care about uninit block because indirect-based + * file doesn't support it. + */ + if (file->physblock == 0) { + if (file->blockno == offset / fs->blocksize) + file->pos = offset; + else + file->pos = file->blockno * fs->blocksize; + break; + } else { + file->blockno++; + } + } + + return retval; +} + +static errcode_t ext2fs_file_llseek_hole(ext2_file_t file, __u64 offset) +{ + ext2_filsys fs = file->fs; + errcode_t retval; + + if (offset >= EXT2_I_SIZE(&file->inode)) + return EXT2_ET_SEEK_BEYOND_EOF; + + file->blockno = offset / fs->blocksize; + + if (file->inode.i_flags & EXT4_EXTENTS_FL) + retval = ext2fs_file_llseek_hole_ext(file, offset); + else + retval = ext2fs_file_llseek_hole_ind(file, offset); + + return retval; +} + errcode_t ext2fs_file_llseek(ext2_file_t file, __u64 offset, int whence, __u64 *ret_pos) { EXT2_CHECK_MAGIC(file, EXT2_ET_MAGIC_EXT2_FILE); + errcode_t retval = 0; if (whence == EXT2_SEEK_SET) file->pos = offset; @@ -323,13 +514,17 @@ errcode_t ext2fs_file_llseek(ext2_file_t file, __u64 offset, file->pos += offset; else if (whence == EXT2_SEEK_END) file->pos = EXT2_I_SIZE(&file->inode) + offset; + else if (whence == EXT2_SEEK_DATA) + retval = ext2fs_file_llseek_data(file, offset); + else if (whence == EXT2_SEEK_HOLE) + retval = ext2fs_file_llseek_hole(file, offset); else return EXT2_ET_INVALID_ARGUMENT; if (ret_pos) *ret_pos = file->pos; - return 0; + return retval; } errcode_t ext2fs_file_lseek(ext2_file_t file, ext2_off_t offset, -- 1.7.12.rc2.18.g61b472e -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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