| Message ID | 1270110626-5018-1-git-send-email-surbhi.palande@canonical.com |
|---|---|
| State | Superseded |
| Delegated to: | Andy Whitcroft |
| Headers | show |
Surbhi Palande wrote: > The following cherry-picked patch fixes the calculation of extents in fiemap. > The commit id in the upstream code is: aca92ff6f57c000d1b4523e383c8bd6b8269b8b1 > This patch fixes bug 474597 on LP. Do consider merging this in Lucid. Surbhi, it would be better to give a quick summary about what the symptom of it is and how the fix affects it here. Saves us going to LP and read through it. ;-) > From dfaa33f0502a8bf9dff0e596783a40ce330c7a9b Mon Sep 17 00:00:00 2001 > From: Leonard Michlmayr <leonard.michlmayr@gmail.com> > Date: Thu, 4 Mar 2010 17:07:28 -0500 > Subject: [PATCH] ext4: correctly calculate number of blocks for fiemap > > http://launchpad.net/bugs/474597 BugLink: ... > > ext4_fiemap() rounds the length of the requested range down to > blocksize, which is is not the true number of blocks that cover the > requested region. This problem is especially impressive if the user > requests only the first byte of a file: not a single extent will be > reported. > > We fix this by calculating the last block of the region and then > subtract to find the number of blocks in the extents. > > Signed-off-by: Leonard Michlmayr <leonard.michlmayr@gmail.com> > Signed-off-by: "Theodore Ts'o" <tytso@mit.edu> > (cherry picked from commit aca92ff6f57c000d1b4523e383c8bd6b8269b8b1) (... upstream) > Signed-off-by: Surbhi Palande <surbhi.palande@canonical.com> > --- > fs/ext4/extents.c | 9 +++++++-- > 1 files changed, 7 insertions(+), 2 deletions(-) > > diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c > index 8b8bae4..f199d20 100644 > --- a/fs/ext4/extents.c > +++ b/fs/ext4/extents.c > @@ -3711,7 +3711,6 @@ int ext4_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo, > __u64 start, __u64 len) > { > ext4_lblk_t start_blk; > - ext4_lblk_t len_blks; > int error = 0; > > /* fallback to generic here if not in extents fmt */ > @@ -3725,8 +3724,14 @@ int ext4_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo, > if (fieinfo->fi_flags & FIEMAP_FLAG_XATTR) { > error = ext4_xattr_fiemap(inode, fieinfo); > } else { > + ext4_lblk_t len_blks; > + __u64 last_blk; > + > start_blk = start >> inode->i_sb->s_blocksize_bits; > - len_blks = len >> inode->i_sb->s_blocksize_bits; > + last_blk = (start + len - 1) >> inode->i_sb->s_blocksize_bits; > + if (last_blk >= EXT_MAX_BLOCK) > + last_blk = EXT_MAX_BLOCK-1; > + len_blks = ((ext4_lblk_t) last_blk) - start_blk + 1; > > /* > * Walk the extent tree gathering extent information.
On Thu, Apr 01, 2010 at 11:30:26AM +0300, Surbhi Palande wrote: > The following cherry-picked patch fixes the calculation of extents in fiemap. > The commit id in the upstream code is: aca92ff6f57c000d1b4523e383c8bd6b8269b8b1 > This patch fixes bug 474597 on LP. Do consider merging this in Lucid. > > From dfaa33f0502a8bf9dff0e596783a40ce330c7a9b Mon Sep 17 00:00:00 2001 > From: Leonard Michlmayr <leonard.michlmayr@gmail.com> > Date: Thu, 4 Mar 2010 17:07:28 -0500 > Subject: [PATCH] ext4: correctly calculate number of blocks for fiemap > > http://launchpad.net/bugs/474597 > > ext4_fiemap() rounds the length of the requested range down to > blocksize, which is is not the true number of blocks that cover the > requested region. This problem is especially impressive if the user > requests only the first byte of a file: not a single extent will be > reported. > > We fix this by calculating the last block of the region and then > subtract to find the number of blocks in the extents. > > Signed-off-by: Leonard Michlmayr <leonard.michlmayr@gmail.com> > Signed-off-by: "Theodore Ts'o" <tytso@mit.edu> > (cherry picked from commit aca92ff6f57c000d1b4523e383c8bd6b8269b8b1) > > Signed-off-by: Surbhi Palande <surbhi.palande@canonical.com> > --- > fs/ext4/extents.c | 9 +++++++-- > 1 files changed, 7 insertions(+), 2 deletions(-) > > diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c > index 8b8bae4..f199d20 100644 > --- a/fs/ext4/extents.c > +++ b/fs/ext4/extents.c > @@ -3711,7 +3711,6 @@ int ext4_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo, > __u64 start, __u64 len) > { > ext4_lblk_t start_blk; > - ext4_lblk_t len_blks; > int error = 0; > > /* fallback to generic here if not in extents fmt */ > @@ -3725,8 +3724,14 @@ int ext4_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo, > if (fieinfo->fi_flags & FIEMAP_FLAG_XATTR) { > error = ext4_xattr_fiemap(inode, fieinfo); > } else { > + ext4_lblk_t len_blks; > + __u64 last_blk; > + > start_blk = start >> inode->i_sb->s_blocksize_bits; > - len_blks = len >> inode->i_sb->s_blocksize_bits; > + last_blk = (start + len - 1) >> inode->i_sb->s_blocksize_bits; > + if (last_blk >= EXT_MAX_BLOCK) > + last_blk = EXT_MAX_BLOCK-1; > + len_blks = ((ext4_lblk_t) last_blk) - start_blk + 1; > > /* > * Walk the extent tree gathering extent information. Ok that seems ok. Acked-by: Andy Whitcroft <apw@canonical.com> -apw
diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c index 8b8bae4..f199d20 100644 --- a/fs/ext4/extents.c +++ b/fs/ext4/extents.c @@ -3711,7 +3711,6 @@ int ext4_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo, __u64 start, __u64 len) { ext4_lblk_t start_blk; - ext4_lblk_t len_blks; int error = 0; /* fallback to generic here if not in extents fmt */ @@ -3725,8 +3724,14 @@ int ext4_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo, if (fieinfo->fi_flags & FIEMAP_FLAG_XATTR) { error = ext4_xattr_fiemap(inode, fieinfo); } else { + ext4_lblk_t len_blks; + __u64 last_blk; + start_blk = start >> inode->i_sb->s_blocksize_bits; - len_blks = len >> inode->i_sb->s_blocksize_bits; + last_blk = (start + len - 1) >> inode->i_sb->s_blocksize_bits; + if (last_blk >= EXT_MAX_BLOCK) + last_blk = EXT_MAX_BLOCK-1; + len_blks = ((ext4_lblk_t) last_blk) - start_blk + 1; /* * Walk the extent tree gathering extent information.